Ali, 35, who lives in East Dulwich with her management consultant husband Simon, combines writing with caring for their two young children, Felix and Shumi.
She found a publisher after writing only two chapters of Brick Lane, and then used her advance to pay for childcare so she could finish the novel.
Ali said: "I worked very intensively - I was obsessed. Any time that I wasn't looking after the kids I was working."
The novel follows Nazneen, a young woman who is trapped in a loveless marriage after arriving in Britain, and seeks solace in a friendship with a young radical.
This year's Orange Prize judges are comedian Sandi Toksvig, library chief Karen Cunningham, Helena Kennedy QC, novelist Minette Walters and Guardian executive Katherine Viner.