Robinho struck in his first game of the season.
Milan boss Massimiliano Allegri said: "Over the past two weeks we have worked more on fitness and hopefully it’ll improve our general performance.
“We were facing an organised Palermo and the overall level of Serie A is very high, so there are no easy tests.
“It’s true we were tired against Juventus, but also played very deep and didn’t move the ball around, so we played badly in Turin.
“Robinho is a player with technique who doesn’t give the opposition any reference points, so it was good to have him back.”