Riley faints after Danny asks her to marry him; and when she wakes up, she has no memory of his proposal. Trying to move on from Riley, Ben decides to find "his Riley" and immediately hits it off with new neighbor Zoey. However, Ben is shocked when their first date reveals he and Zoey have more in common than he thought. Bonnie is determined to finally marry Brad after many aborted attempts, and believing Ben and Danny are to blame, enlists Tucker to help her tie the knot without her sons' knowledge.

Baby Daddy follows Ben, a young man in his early 20s living the life of a bachelor in New York City with his buddy, Tucker, and his brother, Danny. Their lives are turned upside down when they come home one day to find a baby girl left on the doorstep by an ex-girlfriend of Ben's. After much deliberation, Ben decides to raise the baby with the help of his friends and his protective and sometimes over-bearing mother, Bonnie, and his close female friend, Riley.