The club's domestic woes come after a massive summer of investment which saw the likes of Leonardo Bonucci, Andre Silva and Hakan Calhanoglu recruited at an expense of over £150 million.
The Rossoneri have not endured such a difficult start to the season since 1941/42, when they fell to seven defeats from 14 games.
Gattuso, a former midfield general at San Siro, will step up from managing the club's youth side, who have lost just once in their previous five outings.
6 - AC Milan have lost 6 league games so far this season - the last time they collected more defeats after 14 Serie A match-days was in 1941/42 (7). Dismissal.#Montella— OptaPaolo (@OptaPaolo) November 27, 2017
During a trophy-laden playing career, Gattuso also won the World Cup with Italy, and was inducted into the Milan Hall of Fame in 2009.