When Shirley was six, Sylvie sent her down to the corner shop to get her cigarettes during the night. Sylvie gave Shirley a pat on the head and a penny to get some sweets. When Shirley came home, Sylvie left her sitting on the front doorstep in the pouring rain for 20 minutes, while she finished her bath.
When Shirley and Buster were first dating, they tried to keep it a secret. They thought they were doing a good job but Shirley's father Stan Carter knew. Buster went to see Shirley one night at her home, throwing some stones up at her window. When it opened, Stan popped his head out, then he threw out a bucket of fish guts and it landed all over Buster. Buster didn't give up after that, as he was in love with Shirley. "We started hanging around together and doing stuff, Shirley though she was putting on weight, my clothes were getting too tight".
Her mother Sylvie Carter barged into Shirley's bedroom and saw her stomach, she was four months pregnant and didn't even know. Sylvie later pushed her down the stairs to try and abort the baby. When this did not work, Sylvie Carter and Babe Smith decided to pass the baby off as Shirley's brother.
While Shirley was in labour, there was no pain relief in the caravan, and she thought she was going to die. As thunder and lighting raged outside, Babe Smith was doing her best holding Shirley, trying to calm her down. All the time, Shirley was screaming for her mother.
Her mother was off, flirting with a bouncer from the Black Country. When Mick was born, Sylvie came back and Shirley was hoping for kind words or a cuddle. Shirley's mum told her to forget she ever had a son. After he was brought home, Mick was raised as Shirley and Tina's brother. At some point when Mick and Linda were young and in love, Shirley burnt down Linda's mother, Elaine Peacock’s pub.
Shirley did what her mother said and blanked it out. She then met Kevin Wicks, who made her laugh. When Shirley gave birth to Jimbo Wicks, it was like a second chance, until he was diagnosed with cystic fibrosis. The doctors used to strap Jimbo to a board, almost upside down to try and clear his lungs. He'd be coughing, going red. It was like torture. Shirley went with him a couple of times, but just couldn't cope. Shirley blamed herself for Jimbo's condition. After Kevin Wicks died, Shirley found a lump on her breast, she had a biopsy and she could not bring herself to go back for the result for a few months. She later went for the results and it turned out not to be cancer.
Shirley first appears, when, against her former husband Kevin Wicks' wishes, she introduces herself to her adult children, Carly and Dean. Carly is hostile but Dean is amenable, so Shirley moves to Walford to be near them. Kevin and Shirley maintain an antagonistic relationship. Shirley attempts to sabotage his relationship with Denise Fox and threatens to tell her children about their true paternity, which she eventually does: she tells Carly her father is a man named Daniel and Dean that she does not know who his father is. Kevin had brought up Carly and Dean as his own, as well as his natural child with Shirley, Jimbo, who had cystic fibrosis, which Shirley struggled with and ended up walking out on the family, not attending Jimbo's funeral when he died aged 21. The revelation only drives Carly and Dean further away. When she learns that Kevin has been selling cut-and-shut cars, she confronts him. They try to dispose of a stolen car together but are involved in a crash, which kills Kevin. In the aftermath, Carly rejects her mother and leaves Walford. Dean, who gets in trouble with the police, is imprisoned and when released he blames Shirley for all his problems and also moves away.
Shirley begins a relationship with Vinnie Monks, at the urging of her best friend Heather Trott, but the romance eventually ends when Vinnie learns Shirley is harbouring feelings for Phil Mitchell. Phil, an alcoholic, gets drunk with Shirley, uses her for sex and as a surrogate mother for his son, Ben. Shirley falls in love with Phil. She gives him an alibi when he is suspected of murder and helps him get custody of his daughter, Louise, leading to them beginning a legitimate relationship. Shirley is so in love with Phil that she is willing to overlook his misdemeanours. She stands by him when Louise returns to her mother and Phil develops an addiction to crack cocaine. She even forgives him for several affairs, firstly with fellow addict, Rainie Cross and secondly with Glenda Mitchell. In remorse for his wrongdoings, Phil tries to convince Shirley to marry him and she almost does but decides that marriage is unnecessary. She remains with Phil under the proviso that he never cheats on her again.
Shirley's life is thrown into turmoil when her best friend, Heather, is found dead at her flat. Unknown to Shirley, the murderer is Phil's son Ben. Phil tries to cover up Ben's involvement but Shirley grows obsessed with tracing the killer. She finds the murder weapon, a metal photo frame, in a neighbour's house and traces it to a charity shop where it was donated by Phil. She realises that Phil was involved in Heather's death and discusses her suspicions with Ben, who buckles under pressure and reveals information about Heather's death that only the murderer could know. Shirley realises that Ben killed Heather and tries to drown him in the bath, but Phil stops her. Phil convinces her not to call the police but Ben goes to the police and confesses. Unable to cope with Phil's betrayal, Shirley ends the relationship and starts drinking heavily. Phil sees that she needs help and calls Carly, who takes Shirley to stay with her and her son Jimmy. When Shirley returns, she remains hostile to Phil and takes his hush money, despite still having feelings for him.
Shirley and her sister, Tina Carter, move into The Queen Victoria public house, when their supposed brother, Mick, buys it and moves his family to Walford. After 25 years of animosity, Shirley is reunited with her father, Stan. Despite their mutual hostility, Stan gives Shirley £10,000, which she invests in the pub for a 20% share. It transpires that Stan is in contact with Dean. Stan encourages a reunion with mother and son, but Dean remains hostile to Shirley. Eventually, Shirley manages to build bridges with her father and Dean. Shirley grows jealous of Phil's relationship with ex-lover Sharon Rickman. Sharon agrees to marry Phil but discovers that Phil was responsible for a break-in at her bar. Furious, Sharon decides to fleece Phil for his money in revenge. Phil discovers this, confides in Shirley and starts an affair with her, planning to jilt Sharon at the altar and resume a relationship with Shirley. However, Sharon and Phil discover their respective deceptions and ultimately decide to marry. Dejected, Shirley admits her affair with Phil after the wedding and when Phil rejects her, she shoots him. Fearing Shirley's incarceration, Shirley's aunt Babe Smith organises her escape. Dean is distraught and when Mick's partner, Linda, comforts him, and he rapes her. Mick and Dean eventually bring Shirley back to Walford when Stan admits he has terminal prostate cancer.
They meet Shirley's childhood sweetheart, Buster Briggs, and Dean realises that he is Buster's son. They plan to run away together but Mick has Buster arrested for breaking his bail conditions as he is on day release. It is later revealed that Buster is also Mick's father and Shirley is actually Mick's mother, not his sister. Shirley and Mick find Shirley's mother, Sylvie Carter, hiding at Babe's house. Sylvie has Alzheimer's disease and tells Mick she is not his mother but he dismisses this as her being confused. Shirley tries to stop Mick interacting with Sylvie, fearing her secret will be revealed. However, Sylvie is invited to Christmas dinner. Secrets are divulged at the dinner: Linda reveals Dean raped her so Mick tells Shirley before attacking Dean and is only stopped by Shirley confessing that she is his mother, not sister, and that Dean is his brother. The family is split following this revelation as Shirley sides with Dean, believing his version of events. Shirley reveals the reason why she kept her identity as Mick's mother a secret: her pregnancy with Mick was scorned by Sylvie, who attempted to force a miscarriage by pushing her down a flight of stairs. Shirley was forced to raise Mick as her brother and Stan's son, out of fear she would never see him again. Hostilities continue and Shirley struggles to bond with Mick, due to her and Buster's continued alliance to Dean. This results in Shirley being banished from Stan's funeral, despite Shirley having nursed her father through his dying moments.
Shirley learns from Dean that he has a seven-year-old daughter and confronts the child's mother, Shabnam Masood, who continues to lie. Shirley is upset when Linda forbids her from seeing Ollie. Masood Ahmed gives Shirley the address of Dean's daughter, verifying the child, Jade Green, previously Roya, is alive. Shirley finds Jade but discovers she has cystic fibrosis. After Dean decides that Jade is better off without him and Shirley warns that she will fight for custody, eventually gaining Shabnam and Dean's support. When Shirley finds a bra behind her settee, she assumes Buster had sex with Carol Jackson, which Carol does not deny. Shirley nearly throws Buster out and starts considering adopting Jade alone but Carol admits that nothing happened and Shirley helps her come to terms with her mastectomy. Shirley and Buster are awarded custody of Jade after a grieving Shabnam does not contest it. Shirley prevents Dean from raping Roxy Mitchell and, finally believing that he is a rapist, tries to drown him in the bath but he recovers and strikes her as Linda enters. Dean then admits that he raped Linda and goes into hiding. Dean confronts Shirley at Mick and Linda's wedding and attempts to drown her. Mick saves her and Dean, who is then arrested over Roxy. Shirley then encourages Mick and Linda to get married and helps Nancy and Lee run the pub while Mick and Linda are on their honeymoon and has Jade help out to give her some work experience. She is furious when Shabnam turns up overprotective of Jade outside of her visiting hours, but after Masood tells her that Shabnam is unlikely to have any more children, she grows sympathetic and allows Jade to spend more time with Shabnam.
She finds Phil binge drinking, where he admits that he drunk-drove and crashed a car with him, Ian Beale and Sharon's son Dennis Rickman, and Ian took the blame for driving. Shirley encourages Phil to tell Sharon what really happened, and when he eventually does later that night, Sharon ends their marriage. The following day, Shirley learns from Louise that Phil has been rushed to hospital and his liver is damaged. Shirley, Sharon and Kathy Sullivan go to the hospital only to find that Phil has discharged himself. They find Phil drunk at the pub, where he insults his family and hits Kathy. Shirley throws Phil out and admits to Buster that she still has feelings for Phil and is upset as he is risking his health. Buster comforts her and tells her she should move on from Phil because he only cares about himself. A month later, Shirley receives another visiting order from Dean, and eventually decides to visit Dean in prison, to encourage him to plead guilty for trying to rape Roxy. Dean, however, is in denial so Shirley threatens to disown him permanently if he pleads not guilty. The next day, Shabnam tells Shirley, Buster and Jade that she is moving to Ealing so Jade can visit her anytime. In court, Shirley watches as Dean pleads not guilty, much to her disgust. However, due to his failure to surrender to custody on numerous previous occasions, Dean is remanded in custody and a trial in June. Realising that Jade needs protecting from Dean and should be with her mother, Shirley and Buster tell Shabnam that they would like Jade to live with her full-time, giving her full custody, which she accepts. Shirley, unaware that Buster is having an affair with Kathy, is furious when he pays off their acquitted son, Dean, with all their savings, but is later devastated when Buster leaves Walford without saying goodbye to her, whilst she is in the midst of helping Phil end his alcoholism. Mick suggests to Shirley that Buster had an affair with Denise, who is now heavily pregnant. However, when Shirley confronts Denise, Denise confesses she is expecting Phil's son, which is overheard by Sharon.
Babe breaches the pub licence when she inadvertently sells alcohol to an undercover police officer, and the police arrive and arrest Mick, Babe and Shirley. They are formally charged with breaching their pub licence, remaining in custody until their appearance in court the following morning. Shirley later catches Babe stealing money from the safe, and discover that she stolen the entire money that her father left her, Mick and Tina in his will causing Mick to evict her. Shirley and Mick then disgusted to learn that Mick and Linda's son, Lee, has hit his wife, Whitney Dean, during a heated argument. Mick confides in Shirley; she strongly advises Mick to tell Lee that he must leave Whitney, which he does so. Shirley and Tina later have arguments as to whether they should put Sylvie in a home as Shirley does not want to look after her as she can see the trouble Mick is in. Realising Mick will never be able to pay the £20,000 fine ordered by the court, Shirley decides to put the blame on herself and she tells the police she knew Babe was breaching their licence but did nothing about it. She is subsequently charged with perverting the cause of justice. Although the Carters initially think that Shirley will only be in prison for six weeks, they are heartbroken to learn that her sentence has been doubled, meaning that she will stay in prison for three months. Tina visits Shirley in prison to inform her of Sylvie's death which does not seem to upset Shirley but later when her cellmate Debbie Morton teases Shirley about her feelings, Shirley beats her up in their cell.
Shirley is tricked into selling the freehold of The Queen Vic by Max Branning and she forges Mick's signature. Mick is angry when he finds out and The Queen Vic is being controlled by Fi Browning. The Carters are unaware that it is part of a plan by a company, Weyland & Co, to demolish The Queen Vic and redevelop the whole area. The Carters are tricked into debt and are served with an eviction notice, however, they are able to save The Queen Vic when Mick gets involved in a heist and Lee's friend, Callum "Halfway" Highway donates an expensive ring that he stole from the heist.