The former Ottawa goalie won for the second time in two starts for Edmonton since he was recalled from Oklahoma City of the AHL. He spent last season in Russia.
"It's definitely nice to have this one in the bank," said Gerber, who played three seasons with Ottawa, backing up Ray Emery when the Senators reached the Stanley Cup finals in 2007. "It's always emotional to play somewhere you've been around for a while and it was really great to see how the guys competed."
Gerber denied Senators captain Daniel Alfredsson on a short-handed breakaway moments before Tom Gilbert scored a power-play goal late in the second to draw the Oilers even at 1.
"He had a great game," Cogliano said. "He's a really good goalie and that breakaway in the second really kept us in the game and gave us momentum, and I thought he did a great job for us."
Cogliano deflected Brule's slap shot from the left point past Brian Elliott to give Edmonton a 2-1 lead 4:19 into the third. Brule tapped home Cogliano's centering pass at 12:48 to put the Oilers up 3-1. Dustin Penner assisted on both goals.
"I feel comfortable with Pens and Bru," Cogliano said. "I feel like we did a good job defensively all night playing against some pretty good guys in [Mike] Fisher and [Alex] Kovalev, and we were patient -- I think that's the most important thing, patient with the game and did a good job in the third."
Taylor Hall scored into an empty net with 1:55 remaining.
Nick Foligno scored in the first for the Senators, who have lost six of eight.
Elliott stopped 21 shots after recording his second shutout of the season in Saturday night's 3-0 win over Toronto.
"We came out pretty strong and scored the first goal," Elliott said. "That's what you want to do every game but it kind of looked like we got into a lull there and then we took a bunch of penalties in the second period and we got tired out killing all those. It's not the kind of effort we want on any given night. They kept coming and they took their chances and scored."
The Oilers, who lost 4-3 to San Jose on Saturday, play in Montreal on Wednesday night. They wrap up their three-game trip to Eastern Canada on Thursday in Toronto.
Gilbert tied it at 2 with 1:21 left in the second while Ottawa's Chris Neil was serving a tripping penalty. The Edmonton defenseman took Sam Gagner's pass back to the left point and drove a long-range slap shot past Elliott for his fourth goal.
Ottawa took advantage of a couple of breaks to take a 1-0 lead 6:30 in.
Neil's dump-in along the right boards took an odd bounce off the glass and the puck went to Foligno in the slot. Gerber stuck out his left pad to stop Foligno's backhander, but the rebound was redirected into the net off Oilers defenseman Ladislav Smid's skate.
Arena: Canadian Tire Centre Location: Ottawa, Ontario
Referees: Dave Jackson, Frederick L'Ecuyer Linesmen: Jonny Murray, Dan Schachte
Attendance: 17,002 (91.9% full)
Team Stat Comparison
Power Play Goals
Power Play Opportunities
Shots on Goal
Nick Foligno (1)
Assist: Chris Neil
Tom Gilbert (4)
(Power Play) Assist: Sam Gagner
Andrew Cogliano (3)
Assists: Gilbert Brule, Dustin Penner
Gilbert Brule (4)
Assists: Andrew Cogliano, Dustin Penner
Taylor Hall (6)
(Empty Net) Assists: Shawn Horcoff, Jordan Eberle
With a goal on Monday, Taylor Hall now has 12 points through his first 23 games. While far behind the early numbers put up at this point in the rookie seasons of John Tavares and Patrick Kane, Hall is actually producing more than Steven Stamkos did at this point during his rookie season. Stamkos managed 3 goals and 7 assists in his first 23 games.