He served as the general manager and executive vice president of the Chicago Bears of the National Football League (NFL) when they won Super Bowl XX.
[9] His close relationship with then-head coach Mike Ditka factored in his firing by Bears president Michael McCaskey on January 15, 1987.
The rift stemmed from Vainisi and Ditka persuading McCaskey to acquire Doug Flutie, who was the starting quarterback in the Bears' 27–13 divisional playoff loss to the Washington Redskins at Soldier Field on January 3.
[13] In 1995, Vainisi retired from professional football and joined the Chicago law firm Hinshaw & Culbertson, heading the sports and entertainment division.
He worked as a sports agent through Hinshaw & Culbertson and bought Forest Park National Bank.