Amy's mother Roxy Mitchell arrives in Walford with her sister, Ronnie Mitchell, from Ibiza, and they help run their aunt Peggy'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 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 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. Sean, Roxy and Amy drive into a frozen lake, with Sean 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 changes Amy's name from "'Slater" to "Mitchell'", making her Amy Mitchell. She then begins dating local GP Al Jenkins, however their relationship ends when someone complains that he is seeing his patient.
Amy is named after her deceased cousin (now known as Danielle Jones), the daughter of Roxy's sister, Ronnie. Her mother initially decided to raise Amy with her friend Christian Clarke, after Sean missed Amy's birth but changed her mind when she and Sean reconciled. Jack asked Roxy for a paternity test, aware Amy may be his daughter. It transpired that this was so on Christmas Day 2008, which led to Sean abducting Amy, although she was returned to Roxy, by Sean's sister Stacey Slater, on New Year's Day. After it is revealed that Amy is Jack's daughter, Roxy was going to change Amy's name from Amy Slater to Amy Branning but it was never finalised properly on her birth certificate and weeks later after a fall out between Roxy, Jack and Ronnie, Roxy decides to make Amy's name Amy Mitchell and changes it by Law as Sean is not Amy's biological father and Jack isn't on her birth certificate.
In November 2011, Jay and Ben Mitchell are instructed by Roxy to look after Amy while she went out with Kim Fox and Christian Clarke. But after Amy is put to bed, she wonders into the bathroom and almost drowns in the bath but is saved by Yusef Khan when he gives Amy mouth to mouth. 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. Jack then tells Roxy he is taking her to court for full custody of Amy, leaving Roxy distraught. When Amy falls over in the park, Roxy is furious at Jack for getting distracted. 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 their daughter. She threatens to report this, and Jack withdraws his bid for custody and at the court hearing, it is revealed that Roxy has won back custody of Amy and Jack will have to hand her over.
On New Year's Day, Amy went away to Ibiza with her mum auntie. Amy returned (now Abbie Knowles) weeks later with Roxy. Amy lived with Roxy until Roxy was raped by Dean. Roxy felt like she needed a break so handed her over to Jack. Jack and Amy went to live in France for a while. They then came back to live with Ronnie and Matthew, and were later joined by Ricky.
Ronnie nearly adopts Amy but the arrangements were never finalized. Amy was going to move to Essex with her mother, father, aunt, cousin and half-brother, however, when Roxy and Ronnie died Jack decided to stay in Walford . After Matthew leaves to live in Ireland with his biological father Amy's behaviour changes. She starts becoming disruptive at school and does not want Jack to be her dad anymore. Amy cheers up a bit and makes Jack a Fathers Day card. When a nanny comes to visit, Amy and her half-brother spray her with a water gun. Later her half-brother gets gum in her hair, but the nanny gets it out with peanut butter.