Rosie's mother committed suicide when she was young, leaving her with her brother, Clint, and other siblings. Rosie was married to Mike Swann, and they had two children, Mickey and Dawn. While they were still very young, Mike left Rosie and wasn't seen for many years.
Rosie later met Keith Miller, who took on her children as his own before having twins, Darren and Demi. He cannot read and is work-shy. He tends to sit around watching television all day, making excuses to Rosie as to why he doesn't go and find employment.
From her first appearance in 2004, Rosie is seen working hard to support her family. She has a number of cleaning jobs, and takes care of her granddaughter, Aleesha, while Demi and Darren go to school.
In December 2005, Rosie's ex-husband, Mike, is homeless and stays with the Millers'. Rosie and Mike have an affair, and she plans to leave Keith for Mike, taking Darren, Demi and Aleesha with them. Mickey and Dawn find out about this, and Mickey tries to convince her not to leave. Eventually, she decides she cannot take the twins away from their father, and chooses to stay with Keith. Rosie tells Keith about her affair, but does not mention she had planned to leave. Keith forgives her until Dawn lets slip that Rosie had planned to leave. Keith then leaves Rosie.
Keith soon moves back in when he proposes to Rosie, but he doesn't really want to get married and so he keeps putting off the wedding. Rosie, however, doesn't want to wait and the ceremony takes place on 4 July 2006 at Walford Register Office. Keith arrives late and with mud on his suit. Annoyed, Rosie jilts Keith during the ceremony and told him the next day that she no longer loves him and plans to take a job in the Cotswolds. She also wants to take Darren, Demi and Aleesha. They plan to leave the Square the next day but Darren does not want to go. Rosie convinces Keith to make sure Darren goes with them so Keith tells Darren he doesn't care about him. Upset, Darren prepares to leave with his mother, sister and niece. However Rosie can see how upset he is, and decides to tell him that Keith made it all up, allowing Darren to stay in Walford after all.
In July 2008, Rosie sends a letter to Keith about a job. Keith and Mickey then move to the Cotswolds to join her, Demi and Aleesha. It is later revealed that Rosie and Keith have reconciled.