Roxy arrives in Walford with her sister Ronnie, from Ibiza, and they help run their aunt Peggy Mitchell's public house, The Queen Victoria. Roxy's philandering fiancé Damian follows them to Walford, and Roxy seduces him for money so she and Ronnie can buy the local nightclub. However, Jack Branning usurps Roxy, buying the club and going into partnership with Ronnie, whom he also dates. Roxy starts dating Sean Slater, but Ronnie tries to break them up when she discovers Sean is a drug dealer. It later emerges Roxy was once addicted to cocaine. After arguing with Ronnie, Roxy gets extremely drunk and has sex with Jack. She later discovers she is pregnant and tells Sean that he is the father, while she and Ronnie plan to return to Ibiza. They leave, but Ronnie soon returns looking for Roxy, revealing that after they argued in Ibiza, she disappeared. It transpires Roxy is staying with their father Archie Mitchell in Weymouth, to Ronnie's horror. Roxy is adamant she will live with Archie but Sean persuades her to return to Walford, telling her he loves her. They move in together upon their return, and later marry. Roxy goes into premature labour and gives birth to a girl, named Amy, after Ronnie's daughter, who was adopted as a newborn. Roxy and Sean plan to move to Dagenham, but then Sean discovers Jack is Amy's father on Christmas Day. He pretends to forgive Roxy and asks her to move away with him. He drives Roxy and Amy drive to a frozen lake, revealing he intends to kill them all. Roxy gets Amy to safety, but she and Sean fall through the ice. They both survive, and in the wake of this Sean flees. Roxy then begins dating local GP Al Jenkins, however their relationship ends when someone complains that he is seeing his patient.
Archie continually attempts to ruin Roxy's relationship with Ronnie, but it takes Roxy a long time to acknowledge the extent of her father's duplicity and his attempts to destroy Ronnie. Archie is murdered, having made numerous enemies in Walford. Roxy inherits Archie's estate, including £3 million. After Archie's funeral, Roxy meets their younger brother Danny Mitchell for the first time; they invite him to stay. He gains Roxy's trust, but she is unaware that he and their estranged mother Glenda Mitchell are planning to steal her inheritance. Glenda double-crosses Danny, exposing the con, claiming Danny has been abusing her and that he is not really Archie's son. Roxy tells Danny to leave and asks Glenda to stay. Roxy spends frivolously until she only has £20,000 left and this is stolen by her cousin Phil Mitchell and his partner Shirley Carter. Glenda, who is having an affair with Phil, discovers the theft; when Phil dumps her, she urges Roxy to steal back her money as revenge, but they are caught. Phil manages to convince Roxy that it is Glenda who stole her money; he plants money in Glenda's wardrobe and Roxy sends her away.
Roxy agrees to be a surrogate mother for her gay friend Christian Clarke and his partner Syed Masood in 2011, but despite their attempt, she does not become pregnant. Roxy is left mortified upon discovering Ronnie's newborn baby, James, died of sudden infant death syndrome and Ronnie swapped her baby with Kat Moon's newborn, Tommy, who is also the biological son of Roxy's boyfriend Michael Moon. Before Ronnie is tried in court, Michael attempts to frame Ronnie for kidnapping Tommy a second time, to ensure she will receive a custodial sentence. Roxy finishes with Michael as a result, but the damage sticks and, to Roxy's horror, Ronnie is given three years imprisonment. When Ben Mitchell babysits Amy, she almost drowns in the bath when he leaves her alone. She is revived but Jack accuses Roxy of neglect then attempts to gain custody of Amy; he is awarded this temporarily and stops Roxy having any contact with Amy. Roxy hires a solicitor, Jimmie Broome, who suggests she discredit Jack. The animosity has a negative effect on Amy, so Roxy and Jack agree not to argue in front of her. They momentarily soften towards each other, which leads to sex, but after Roxy discovers Jack has forged her signature to get Amy a passport, she believes he is intending to flee the country with her daughter. She threatens to report this, and Jack withdraws his bid for custody; Amy is returned to her mother.
Roxy is comforted by her friend and boss, Alfie Moon, after her attempts to seduce Max Branning are made public. Realising she has feelings for Alfie, she confesses she loves him. Although Alfie admits to being tempted, he remains faithful to his wife Kat, who is away visiting family. Roxy and Alfie remain friends and colleagues despite Roxy's growing affection for him. After Alfie goes to visit Kat, Roxy becomes concerned for Jean Slater's welfare and asks Alfie to return home. He returns with Kat, who throws Roxy out. Seeing that Alfie is in financial difficulty, Roxy gives him a loan from Amy's Child Trust Fund. Suspicious of Roxy and Alfie's friendship, Kat confronts Roxy and she admits she had a crush on Alfie. Kat sacks her from the pub and she moves back in with Phil. Phil once again takes control of the Queen Vic kicking Kat and Alfie out due to unpaid rent. He then appoints cousin Roxy as manager once again running it alongside Alfie and Kat. Roxy has brief flings with AJ Ahmed and Michael, who she moves in with for a short time. When Alfie and Kat split up, Alfie asks Roxy to live with him and they declare their love for each other. Roxy is delighted when Alfie decides to divorce Kat, though it leads to more hostility between Kat and Roxy, which leads to a physical fight.
Roxy and Alfie decide to try for a baby and Kat is upset about this. When a builder, Josef, tries to steal money from the pub's till and later the safe, Kat helps Roxy to stop him and Roxy thanks Kat but then accuses her of trying to win Alfie back. Initially Kat promises Roxy that she will not tell Alfie about the incident, but when Roxy tells Janine Butcher that Kat is having a relationship with her estranged husband Michael, Kat tells Roxy that she has to tell Alfie about the attempted robbery. Roxy is later delighted when she discovers that Kat and Alfie's divorce has been finalised, but is upset when Alfie does not tell her about it. Alfie proposes to Roxy and she accepts.
Roxy does not tell Alfie that Ronnie is due to be released from prison soon, but when he finds out, he forbids Roxy from meeting her at the prison gates. Instead, Kat meets Ronnie and brings her back to Walford. Ronnie and Roxy spend time together while Alfie is out, but he returns early to find them together, so tells Roxy to choose between him and Ronnie. Roxy chooses Alfie, but is miserable, so starts seeing Ronnie in secret. Michael sees them and tells Alfie, who nearly ends his and Roxy's engagement, but instead, tells Roxy they must leave Walford immediately to sort out their relationship. When they return, Roxy tells Ronnie she can no longer see her, but Alfie sees Roxy crying, so announces their wedding date and invites Ronnie to the wedding. Alfie and Ronnie spend time together, but she is suspicious that he still has feelings for Kat, and warns him not to hurt Roxy. However, after the death of Michael, even Roxy notices how Alfie looks to Kat for comfort. At Roxy's hen party, Ronnie expresses her doubts about the upcoming marriage to Roxy, and the sisters argue. This leads to Roxy declaring that she does not want Ronnie at the wedding. Ronnie attends anyway and the sisters reconcile. Kat walks in during the ceremony, but Alfie continues his wedding vows and they marry. However, Roxy soon realises that Alfie still loves Kat and orders him to go to her as she is leaving for Ibiza. He does so, and Ronnie and Phil worry about Roxy, who gets drunk and humiliates herself. Phil then gets revenge on Alfie on Roxy's behalf by selling The Queen Vic. Roxy has sex with Carl White and they begin a relationship, much to Phil and Ronnie's annoyance, especially as Roxy is not looking after Amy. Ronnie tries to get Carl to break up with Roxy, and when he refuses, she buys tickets for her and Roxy to return to Ibiza. Carl tries to outmaneuver Ronnie by inviting Roxy on a holiday of his own, but when he fails to turn up Roxy leaves with Ronnie for Ibiza instead.
They return to Walford three months later and Ronnie confesses to Roxy that the reason Carl didn't show up to take her away was because Ronnie had murdered in him in self-defence several hours earlier. Despite initially struggling with the confession, Roxy forgives her sister, and together they buy their own house on the square. When Carl's mother, Nora, arrives looking for Carl, Roxy wants to help convince her that Carl has moved away from Walford, but Ronnie intervenes and pretends to be her instead. Ronnie pays Aleks Shirovs to date Roxy, but she becomes distrusting of him and tells him to stop. Aleks continues to date her and falls for her, acting as a father-figure to Amy. Roxy discovers that Ronnie was paying Aleks to date her, but eventually forgives Aleks when he declares his love for her publicly. When Alfie tells her that Aleks is married to Marta Shirovs and has a daughter, Ineta, they break up. Aleks convinces her that they have separated. Ronnie warns Roxy about her being a mistress; she orders her to give him an ultimatum. She does, and he arranges a holiday.
On her wedding day to Charlie Cotton, Ronnie goes into labour. On the way to the hospital, Roxy, Charlie and Ronnie are all involved in a car accident as the vehicle crashes. Emma Summerhayes is killed after being run over by the car and Ronnie is seriously injured and comatised. While Ronnie is in her coma, Roxy and Charlie have sex, later agreeing that it was a mistake. Later, Charlie learns that Roxy has feelings for him. Aleks finds out that Roxy and Charlie had sex, and he and Roxy make plans to leave for Latvia immediately, but they split after Roxy admits to Aleks she does not love him, so Aleks leaves with Marta and Ineta. Charlie admits to Roxy that he thinks he is falling in love with her but says they should stay apart. Roxy confesses to Ronnie about her one-night stand, and their relationship becomes strained. Roxy turns to drink and has sex with Dean Wicks, later admitting that she likes him. She asks Dean to keep their relationship secret, due to him being hated by the community for raping Linda Carter. Ronnie discovers their relationship and tries to stop them from seeing each other. However, they carry on seeing each other. Whilst Dean is hiding from Ronnie, he finds the hidden camera Ronnie is using to spy on Roxy and Charlie. When Ronnie threatens him, Dean tells Roxy about this, and, when Roxy confronts Ronnie, they argue, then Roxy moves in with Dean. When Ronnie and Charlie's marriage begins to fall apart after Ronnie has sex with Vincent Hubbard, Roxy tries to convince Ronnie to repair the marriage for Matthew's sake. However, when Amy is due to go to France to visit Jack, Charlie asks Roxy if they can join her. After Roxy drops Amy off at the airport the next day, she learns that Charlie wants to take Matthew with them. Although initially hesitant, she says she wants to come with him. However, when she learns that Ronnie has been prescribed anxiety medication, she tells Ronnie the plan and they conspire against Charlie together. Roxy is stunned when Dean, jealous of Charlie, burns her with a hair straightener. Dean becomes insecure that Roxy is spending time working with Masood Ahmed, so employs her as manager of his salon. When she says he needs to take himself less seriously, Dean cuts a chunk out of her hair in anger, but immediately apologises and proceeds to give her a proper haircut. As a result of this, Ronnie worries about Dean trying to control Roxy. Roxy and Ronnie have a furious row over Charlie and Dean, which turns violent.
Roxy then reports Ronnie's murder of Carl to the police. This results in Roxy fighting with Sharon Mitchell as the Mitchells despair of Roxy not seeing Dean as a rapist. When Jack returns, he finds out from Mick Carter that Dean raped Linda, so he packs Amy's belongings and removes her from Roxy's care, pointing out that Roxy's feisty personality has gone since she started dating Dean. As Roxy ends her engagement to Dean, who has assaulted her again, he attempts to rape her but Shirley interrupts. A tearful Roxy is found by Linda and her mother Elaine, who support her. Linda encourages her to tell the police, which Roxy does. Shirley then attempts to drown Dean who finally admits he raped Linda before running away from the police. Roxy is examined in the hospital with bruises and scars left by Dean on her body, and gives her statement. Roxy visits Glenda and decides to leave the country, but Glenda enlists Ronnie to try to stop her. They are unsuccessful after Roxy tells Ronnie she has controlled her all her life and she needs to be alone. Roxy leaves Amy with Jack, who also departs Walford shortly after, in January 2016. One month later, Roxy does not return for Dean's court case, where he pleads not guilty and is remanded in custody until a retrial in June, so Ronnie calls her to inform her of this.
She returns in May having been assaulted. She is hospitalised but discharges herself. Glenda has also returned, looking for Roxy as she took money from her and Danny before disappearing. Roxy tells Ronnie that she needs money to pay off a debt, so Ronnie gives her money, and Roxy gives some of it to Glenda as long as Glenda never returns to Walford. Roxy leaves, and when she returns, she tells Ronnie her debt is paid and she has money coming in. Jack refuses to let her see Amy. Roxy appears in discomfort and pain, and tells her relative Billy Mitchell that she has £10,000 worth of cocaine inside her and she thinks something has gone wrong. Jack and Jay Brown find out, and when Roxy passes the bags of drugs through her system, she tells Jack and Billy she has flushed them but reveals to Jay that she has kept them, and he offers to help her sell them. However, they both change their minds for the sake of their families, and Roxy puts effort into finding work, and agrees to help Donna Yates on her market stall. Roxy starts a relationship with Andy Flynn but Roxy struggles with being intimate because her last relationship was with Dean, and she admits that she is not ready for a relationship. She later learns that Andy is in fact Gareth Jones, Ronnie's dead daughter, Danielle‘s adoptive brother, who has been plotting revenge on Ronnie as he blames her for Danielle's death. Despite Andy telling Roxy that his feelings for her were genuine, she firmly believes that he used her to get to Ronnie and she coldly tells him to leave. Roxy is then left further distraught along with Linda when Dean is later found not guilty, despite Roxy and Dean's mother Shirley giving testimony in court.
Roxy struggles to be a good mother to Amy, especially when Ronnie suggests that Roxy take Amy shopping, but not knowing this, Jack books a trip to Paris, which upsets Roxy when she finds out, and when Roxy wants to buy an expensive gift for Amy's birthday, her credit card is declined. Roxy asks Ronnie to lend her the money, so Ronnie asks her to help Amy with her homework but afterwards Roxy says she enjoyed it so much she does not want any money for it. Roxy is then upset to discover that Ronnie and Jack plan to move out of London, taking Amy with them. Roxy is also angry when Jack decides to sell the house Ronnie and Roxy co-own, but he tells her she well get half of the money from the sale. Donna helps Roxy to realise that letting Amy live with Jack and Ronnie will be the best thing for Amy, but then Roxy suspects Jack of having an affair with Billy's partner Honey Mitchell and tells Ronnie this, but Jack denies it. Roxy also agrees to move away to be near Amy but soon changes her mind. Roxy fears that Amy will not remember her, and she starts drinking heavily but when Phil tells her off and she forgets to collect Amy from school, she realises her problems and asks Donna if she can change. Donna suggests that the best thing she can do for Amy may be to allow Ronnie to adopt her. After an emotional discussion, Ronnie agrees to the adoption. Roxy then starts using drugs again. On Ronnie's hen night, Roxy tells Ronnie that she is not going to the wedding and will be in Tenerife instead. Ronnie insists that Roxy is at the wedding and also asks her to move to Essex with her, Jack and Amy. A few nights later, Roxy embarrasses herself at the market traders' party after taking cocaine. She calls Glenda, who collects her.
Roxy returns a day later to pack her things and refuses to go to Ronnie's wedding in fear she will ruin it, saying she is going to move in with Glenda and Danny. However, she changes her mind after Ronnie shows how much Roxy means to her. At the wedding, Roxy agrees to give Ronnie away but is uncertain once more, believing Ronnie needs to tell Jack the truth about Roxy moving away with them before marrying him. Ronnie dismisses this, but runs off in tears when walking down the aisle. Roxy makes Ronnie tell Jack, who understands that Ronnie needs Roxy and agrees to let Roxy come with them. At the wedding party, Roxy and Max dance and flirt, and she afterwards, they go to her room for sex but are interrupted by Ronnie, who asks Roxy to join her while Jack reads the children a bedtime story. Ronnie and Roxy reminisce about their time on the square and talk optimistically about their future whilst getting increasingly drunk. They find the hotel's swimming pool and Roxy jumps in. Ronnie is shocked to see her unconscious at the bottom of the pool and attempts to rescue her, but her wedding dress weighs her down and she drowns alongside Roxy. Later, Jack is informed that Roxy suffered a heart attack in the pool and he surmises cocaine was to blame. After their funerals, an inquest into the deaths concludes that Roxy drowned, following a cardiac arrest when hitting the cold water and both deaths are ruled as misadventure, however, Jack still blames Roxy's drug use for Ronnie's death.
In 2019, Roxy's ex-husband Sean returns to Walford and picks Amy from school. He hopes to reunite with Roxy, unaware of her death. Jack takes Sean to Ronnie and Roxy's grave where he reveals this to Sean. Jack blames Roxy's drug use for Ronnie's death which leads to them fighting by their grave. Sean wears his and Roxy's wedding ring and he later speaks to Roxy's gravestone where he tells her that he will join her. Roxy's voice is later heard when Sean replays an old voicemail left by Roxy when they were married.