Soriano hit a tiebreaking, three-run homer in the seventh inning and Chicago rallied after blowing a five-run lead, beating the Houston Astros 11-7.
Soriano's 20th home run highlighted a five-run burst and sent the NL Central-leading Cubs to their eighth victory in 10 games.
"It's great," Soriano said. "I work hard for those moments. I like those moments. It's special today. ... That's what I want to do, try to help the team win."
Besides the dramatic homer by Soriano, the Cubs also got a boost by the return of Kerry Wood. The All-Star closer got a loud ovation and then pitched a scoreless eighth after missing three weeks with a blister on his right index finger.
The late drama came after the Astros beat the Cubs 2-0 in eight innings the previous night. That game was delayed twice by violent storms before finally being called just before midnight because of thunder and lightning.
Soriano drove in four runs. The Astros, who came back from a 6-1 deficit to take the lead, had their four-game winning streak stopped.
Lee's 26th home run, a two-run drive off Howry with two outs in the seventh, gave Houston a short-lived 7-6 lead.
Doug Brocail relieved and Soriano, who had singled and doubled, drove a 1-2 slider over the wall in left-center.
"It looked like a damn heater," said Brocail, who wanted to bounce the pitch. "I missed my spot. He got it."
The Cubs added another run in the inning when Ryan Theriot walked, stole second and scored on Derrek Lee's single.
Soriano has 18 hits in his last 43 at-bats after going 3-for-5 on Tuesday and has stabilized the lineup after returning from a six-week stay on the disabled list with a fractured finger late last month.
"The most important thing to me is to stay healthy," said Soriano, who spent time on the DL earlier in the season with a strained right calf. "My health is good. I can do whatever I can to help the team win. I'm very happy I'm back in the lineup."
So is DeRosa.
"He makes a huge difference," DeRosa said. "It changes the game. He's one of the big superstars in the game. I think moreso than his ability to hit the ball out of the ballpark, he loosens us up with his charisma and character before and after the game. He's a huge part of who we are."
Howry (4-4) got the win despite allowing two runs in 1 1/3 innings. Carlos Marmol pitched a perfect ninth.
Harden allowed five runs and eight hits in 5 2/3 innings, tying season-highs, after four dominant starts for Chicago following last month's trade from Oakland. He struck out eight and walked one.
Astros starter Wandy Rodriguez had another rough outing. He lasted just five innings, allowing six runs and nine hits in his second straight start.
"He didn't really have good command, I'll say that much, and sometimes when you don't have command and you don't make quality pitches it hurts you sometimes," manager Cecil Cooper said.
- Wood, who was activated from the DL, had little to say other than, "It's great to be back." To make room, the Cubs designated LHP Scott Eyre for assignment.
- Astros OF Michael Bourn, who was out of the starting lineup for a ninth consecutive game, said his sprained right ankle was feeling better and he hopes to return to the lineup on Thursday at Cincinnati.
- 1B Lance Berkman, who was scheduled for a day off, entered the game on a double switch in the seventh and was 0-for-1.
- Cooper said he would like to rest SS Miguel Tejada on Wednesday.