The 40-year-old 'Butter' actress - who is married to Ben Affleck, 40, with whom she shares three children, Violet, seven, Seraphina, three, and Samuel, 10 months, - beat off stiff competition from Beyonce, Reese Witherspoon and Jessica Simpson to be awarded the title by Today's Parent magazine.
According to the magazine, Jennifer won "by a landslide" as she manages to be relatable to other mothers by admitting she sometimes struggles to juggle her family and career but still looks "gorgeous and put-together."
Jennifer's husband Ben recently revealed he still can't believe she married him and said the secret to a successful marriage is choosing someone who is out of your league.
He said: "There are two things for a marriage to be good. One is to work hard on it. The other one is to marry above you. And I succeeded at both of those."
The 'Argo' actor-and-director admitted his wife was "cool" with his hectic schedule and says he appreciates how she stays up late waiting for him to come to bed so they can brainstorm ideas about whatever new film he's working on.
He explained: "My wife is very cool. She knows that directing is consuming in that way. She's just happy I come home. Usually, I come home after the kids are in bed anyway. We like to chat for a little bit and I'll talk about the movie and what I'm doing, what I'm thinking or whatever. She's a good sounding board."