The Italy midfielder, who started his career as a second striker but has dropped deeper and deeper in recent seasons, let fly from almost 40 metres on 26 minutes and the ball flewto the top corner of the net.
Milan moved onto 11 points from six games ahead of champions Inter Milan, on 10, who host rivals Juventus in the pick of Sunday's main programme of matches.
"It's our first win away from home," captain Gennaro Gattuso, reborn this term having almost left for Olympiakos in the close season, told Sky. "We are still a team which is rebuilding and there's lots more to do."
Massimiliano Allegri's side were good value for their victory given an array of attacks and only poor finishing from forwards Zlatan Ibrahimovic and Robinho stopped them from extending their advantage in the first half.
Ibrahimovic, who had scored five goals in all competitions since his arrival from Barcelona, recovered from a minor knock to start but often drifted to the left in the first half with Ronaldinho returning to the lineup just behind the front two.
The Brazilian, who normally operates on the left, went close twice in the second half while Robinho again missed the target before being replaced by the fit-again Alexandre Pato.
Parma were quiet apart from a late onslaught although ex-Milan forward Hernan Crespo had an early appeal for a penalty turned down after Alessandro Nesta's challenge.
In the early game, Medhi Benatia scored deep into stoppage time to seal bottom side Udinese's first win of the season with a 1-0 home victory over Cesena.
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