The experienced midfielder has offered the Rossoneri coach his backing amid ongoing rumours that he could be on his way out
There have been question marks over whether the 45-year-old will remain at the San Siro side beyond the current season, but Ambrosini believes Allegri deserves to stay following his good work in the past few seasons.
"The coach has done well to remain calm in a difficult moment and managed to transmit that calmness to the players," Ambrosini told Sky Sport 24.
"It would be a big decision to part company with a coach who has achieved some important results in the past three years and has met the club's objectives - if we finish third in the table this season.
"I think that Milan should confirm Allegri as coach for next season. We will see what happens in two weeks.
"A lot will depend on what the president wants. When he has something in mind, it's difficult to get him to change his plans."
Allegri has been in charge of Milan since the summer of 2010 and has since guided them to one Serie A title.