Kevin Durant and Russell Westbrook propelled the rising Thunder while leaving the storied Lakers franchise in a state of uncertainty after completing the 4-1 best-of-seven series win.
Durant and Westbrook combined for 53 points and the home team withstood 42 from Kobe Bryant to set up a West final against the top-seed San Antonio Spurs.
"It's a step in the right direction. The Lakers are an unbelievable organization," Durant said. “It feels good to advance, but we have to keep going."
The Thunder had moved into position to eliminate Los Angeles with fourth-quarter comebacks in Games Two and Four but they dominated late in the clincher to punctuate their triumph.
Oklahoma City trailed 70-66 midway through the third but finished the quarter with a 17-7 run, then rattled off the first 10 points of the fourth, most with Bryant sitting on the bench.
Pau Gasol bounced back from a rough Game Four with 14 points and 16 rebounds, but it was far from enough for the visiting Lakers.
The younger and hungrier Thunder outmuscled Los Angeles in the rebounding battle and dominated in the fast break.
And while LA flopped to a second-round loss for the second year in a row, Oklahoma's players paid tribute to Bryant, who many of them grew up idolizing.
“It means a lot," said Thunder guard James Harden, who had 17 points. "Kobe's a warrior out there, and it's tough. But we stuck with it."
In the East, Brandon Bass scored 27 points to spark the
Bass found his shooting touch in the third quarter, where he scored 18 points to net a play-off career high and help the Celtics pull away from the 76ers.
“"When you're on a team with a point guard like (Rajon) Rondo, the ball just happens to find you," Bass said. “We have to come out (in Game Six) with the same defensive approach."
The Game Five win gave Boston a 3-2 lead in the best-of-seven second-round series.
Kevin Garnett added 20, while Rajon Rondo tallied 13 points and 14 assists for Boston, who trailed early but outscored the 76ers 54-35 in the final two quarters.
Elton Brand lead Philadelphia with 19 points. Game Six is on Wednesday in Philadelphia.