Mike Fontenot hit a two-run double and Marlon Byrd added a tie-breaking RBI double to back Silva, who leads the team in wins. The Cubs improved to 6-1 in his starts.
"He throws a lot of strikes. He's around the zone," catcher Geovany Soto said. "He's not afraid to pitch to contact. He keeps the ball down -- he's been great for us. The biggest thing is he's always around the zone."
Acquired from the Seattle Mariners for Milton Bradley in December, Silva is the first Cubs pitcher to start 4-0 since Ryan Dempster did so in 2008. Silva scattered seven hits over 6 1/3 innings, striking out two, and was aided by three well-timed double plays -- one recorded after he left in the seventh.
"It's really nice to have a good record," Silva said, "but I've gotten a lot of run support, and that helps me a lot. You see the way Ryan Dempster and [Randy] Wells [have pitched]. Dempster should have five, six wins already. That's the way baseball is. I'm happy because I know I've been making my pitches and I know I'm making improvement."
The win snapped a four-game losing streak, and the four runs were a nice change after the Cubs averaged two runs a game in their last seven contests.
"I'll sleep better tonight," Byrd said. "It feels like we haven't won a game in three weeks."
The Marlins made it interesting in the ninth against closer Carlos Marmol, adding an RBI single by pinch-hitter Brian Barden. Florida had two on and two outs when Marmol struck out Hanley Ramirez to end the game and pick up his first save since May 1.
"We had some chances there in the seventh with guys we wanted at the plate," Marlins manager Fredi Gonzalez said. "The same thing in the eighth and the same thing in the ninth. We didn't get those runs in. [Winning] two out of three was good."
Marmol didn't blame his layoff for the rough ninth.
"You have to go out there and pitch," he said. "It doesn't matter what the score, if it's a save situation. I haven't had too many opportunities to save, but I have to put in my mind to go out there and pitch."
The Cubs took a 2-0 lead in the second when Soto was safe on a fielder's choice and moved to third on Alfonso Soriano's double before both scored on Fontenot's double.
Ronny Paulino tied the game at 2 in the fourth with a two-run single with two outs. Kosuke Fukudome walked with one out in the Chicago fifth, and Starlin Castro singled to set up Byrd's RBI double. Castro then scored on a wild pitch by Chris Volstad (3-3), who crossed up Paulino, his catcher.
"I threw a changeup," Volstad said. "It was supposed to be a curveball."
Silva is throwing strikes and has exceeded expectations. This is a pitcher who was a combined 5-18 in the last two seasons in Seattle.
"I feel like I'm helping my team now," said Silva, who began his Cubs tenure on a high note because of the positive vibe he felt at the team's Fanfest in January. "I feel good because I feel like I'm somebody now, like my team can count on me. That makes me feel good and important."
He's trusting his stuff, and on Wednesday, picked up his fifth quality start. It also helps that the Cubs finally scored. They're now 14-4 when scoring four or more runs in a game.
"We needed it," Derrek Lee said. "But more important, we have to continue it."