Brazilian midfielder Serginho scored the only goal of the match 12 minutes into the game as the Rossoneri took the first derby encounter against Inter at the Giuseppe Meazza.
It was a home fixture for Milan and it seemed to pay dividends against Hector Cuper's side, as both teams look set to contest the title with Scudetto holders Juventus this season.
Milan's victory was well-timed as Juve were held to a 1-1 draw by Bologna at the Stadio Delle Alpi in the early Saturday match in Serie A.
The Scudetto holders went behind mid-way through the second half when Giuseppe Signori scored from the penalty spot to give the visitors the lead.
However, the Turin giants equalised with four minutes remaining as Mark Iuliano scored for the Bianconeri.
The draw - along with Milan's derby win - means that both sides go level on points at the top of the Italian league, with Inter two points behind their two rivals.
Click below for match stats:
Serie A
Milan 1-0 Internazionale
Juventus 1-1 Bologna
Click here for an updated Serie A table.
