Ryan Smyth, Marc-Andre Bergeron, Marc Pouliot, Joffrey Lupul and Raffi Torres scored for Edmonton while Eric Belanger had the lone response for Atlanta. The Oilers (28-24-4) have now won five of their last seven games to move to within six points of both the final playoff spot in the Western Conference and top spot in the Northwest Division.
Atlanta (30-20-9) has lost two in a row and five of its last six.
The Thrashers kicked off the scoring just 5:15 into the first period as Belanger scored in his first appearance in the Atlanta lineup, flicking a shot through the legs of Oilers starter Dwayne Roloson.
The Oilers tied the game 1-1 with a power-play goal just before the halfway point of the first. Shawn Horcoff picked up the puck during a scramble in the crease and slid it to Smyth, who tucked his 28th of the year under the pad of Atlanta goalie Johan Hedberg.
Edmonton took the lead 7:30 into the second period as Ales Hemsky found Bergeron creeping in to the high slot, and he unleashed a rocket that beat Hedberg glove side to give the Oilers the 2-1 advantage.
Edmonton stretched that lead to 4-1 with two quick goals just past the halfway point of the second. Rookie Pouliot got the first one when he sent a wrist shot through a maze of players into the Thrasher net and Lupul followed up just over a minute later when he beat Hedberg in a race to the puck behind the Atlanta net and banked a shot off the netminder's pad.
Edmonton made it 5-1 with just under five minutes to go when Torres salted the game away on the power play.
Roloson stopped 29 of 30 shots for the win.
Atlanta had two potential goals called back due to goaltender interference
Both teams return to the ice on Tuesday as Atlanta plays the fourth game of their current six game road swing in Calgary and Edmonton begins a season high seven game road trip in Boston.
NOTES: Newly acquired Thrashers forwards Belanger and Denis Hamel played for their new team for the first time. Belanger was acquired on Saturday from Nashville for Vitaly Vishevski while Hamel was snagged from Ottawa through waivers. . . . The last time these two teams played a game in Edmonton was three years ago to the day. The match concluded with a 12-player line brawl that included goalies Ty Conklin and Pasi Nurminen trading blows. . . . Horcoff has picked up his game of late for the Oilers. He has three goals and six points in his last four outings as part of his current four-game scoring streak. . . . Oilers forward Fernando Pisani left the game five minutes into the second and did not return after suffering a mild concussion on an open ice hit up by Andy Sutton.