The `Heroes` actress - who married stand-up comedian Hayes McArthur last August - will reportedly welcome the new addition to her family into the world this winter.
Her spokesperson confirmed: "Ali and Hayes are thrilled to be expecting their firstchild."
Ali, 34, has previously admitted that she was desperate to settle down and have children with Hayes from the first time they started dating.
Speaking after their engagement in 2007, she confessed: "I told Hayes after three weeks that I wanted to marry him and that we could do it tomorrow. I look forward to the time that I`m at home with babies.
"He has brought light to my life. I feel lucky every morning when I wake up and see him. Not everybody is fortunate enough to find their soul mate in life."
Ali has also previously admitted she ruined several relationships before she met Hayes because she was so obsessed with getting married.
She said: "Since I was 15 years old, all I wanted was to find the guy I was going to marry. My heart got broken so many times because I put so much pressure on it. And then I got blindsided.
"Hayes showed me the way, and all was right. This is how it`s supposed to be."