Emanuelson converted on an running attack with teammate Stephen El-Shaarawy in front of a crowd of 57,748.
"We were standing good on defense, when we got the ball there was a lot of space to go to the goal," Emanuelson said.
"It always feels good to score. Tonight was a good test for us. We played well and I'm happy that I scored a goal."
Emanuelson dribbled the ball deep toward the Chelsea penalty area and then passed toward the left wing to El-Shaarawy.
El-Shaarawy took a shot but the ball hit a Chelsea defender and bounced back to Emanuelson, who beat Chelsea goalkeeper Petr Cech with a hard shot.
"Last year I played a lot of games and now it's a chance to build on that," Emanuelson said. "I want to feel important."
Eden Hazard had Chelsea's best attempt to tie it with four minutes left in regulation but his free kick from the half circle soared over the crossbar.
Emanuelson also had a excellent scoring opportunity in the 52nd minute but his left-footed shot was saved by Cech.
The Blues controlled the offence at the start of the game. They also had more spark Saturday than they did in a 3-2 loss to the Major League Soccer all-star team in the middle of the week.
Milan played without star striker Robinho, who was not allowed to leave Brazil due to a passport problem.
Robinho is expected to join Milan for an exhibition match against Real Madrid on August 8 at Yankee Stadium.
"I'm very happy the way the team played," Milan coach Massimilano Allegri said. "This is a team that has to grow and this was a very good step."
European champs Chelsea now head back to England for a friendly against Brighton and then the traditional Charity Shield contest against league champions Manchester City on August 12.
"This is what pre-seasons are for, these are games to give young players a chance," Chelsea head coach Roberto DiMatteo said.
AC Milan, who arrived in the USA on Friday, play their next game in the nine-match 2012 World Football Challenge against Real Madrid.
Saturday's crowd was the highest attendance so far of the World Football Challenge.
Source: AFP
Source: AFP