Two goals from striker Charlie MacDonald in the first 48 minutes set Orient on their way to an impressive victory over promotion-chasing Bournemouth, who slipped to their fourth straight defeat.
Cherries substitute Brett Pitman pulled a goal back midway through the second half, but Orient wrapped up a deserved victory when Kevin Lisbie made a dramatic return from injury and fired home a third 11 minutes from time.
That put the seal on a excellent win for the home side in front of 5,136 – their biggest home gate for a league game this season and lifted the O’s to 11th place in the table.
Orient manager Russell Slade made two changes to the side that took a point at Sheffield United on Tuesday night, as David Mooney and MacDonald returned up front, while Shaun Batt, who ploughed a lone furrow at Bramall Lane was ruled out through injury.
Jimmy Smith dropped to the bench, where he was accompanied by fit-again Lisbie, who had missed the last 13 games with a hamstring injury.
The first half was a thoroughly entertaining affair as both sides attempted to get the ball down and play, but despite the quality of the football clear-cut chances were few and far between.
Orient’s leading scorer Mooney had the first effort on 13 minutes, but dragged his shotwide, before the home side cashed in on their dominance with the all-important breakthrough.
It arrived on 26 minutes when Mathieu Baudry, who was in excellent form against his former club, set Mooney clear down the right.
The ball looked to be heading out of play, but unlike the Bournemouth defence, the O’s striker refused to give up the chase and kept it in before crossing for MacDonald to fire home close range.
O’s continued to press and Scott Cuthbert, looking to join the attack at every opportunity down the right, poked a shot across goal.
But Bournemouth regrouped and enjoyed a good spell as the half drew to a close and almost levelled on 35 minutes when defender Dan Seabourne sent a header from Marc Pugh’s cross thudding against the crossbar.
Orient managed to smuggle the ball to safety as referee James Linington waved away the visitors’ optimistic claims that the effort had crossed the line.
Slade’s side weathered the brief storm and almost stretched their advantage just before the break when Lloyd James’s cross-field pass found Cuthbert and his cross was nodded into the path of Romain Vincelot by Mooney, but the Frenchman’s fierce volley fizzed just over the bar.
Bournemouth, who had lost top spot and had drifted down the table after three successive defeats, started the second half disastrously as a defensive lapse allowed MacDonald to drive through the centre of the visiting rearguard and fire the ball home past the advancing Shwan Jalal for his third goal in Orient colours.
The strike seemed to shake the visitors and Mooney could have made it three on 54 minutes, but failed to hit the target when he fired a quickly-taken free-kick from James across the face of the goal.
But the Cherries hit back and only a spectacular save from Jamie Jones on the hour preserved Orient’s two-goal cushion when he acrobatically tipped away substitute Brett Pitman’s header from eight yards.
The introduction of Pitman for Wes Fogden on 55 minutes lifted the visitors and it was no surprise when they pulled a goal back on 66 minutes when Eunan O’Kane’s cross from the right found Cuthbert outnumbered at the far post and the Bournemouth substitute sent a superb volley into the net from a tight angle.
That was enough for O’s boss Slade to make a change himself as he threw Lisbie into the fray 20 minutes from time in place of Mooney and the veteran hitman made an indelible mark just nine minutes after his introduction.
Moses Odubajo went on a wriggling run down the right and cut the ball back to Lisbie, who fired home his 10th league goal of the season from 12 yards, to set the seal on a dream comeback and end Bournemouth’s revival hopes.
Orient: Jones; Cuthbert, Baudry, Clarke, McSweeney; Odubajo, Vincelot, James (Smith 78 mins), Cox; MacDonald (sub Obafemi 90 mins), Mooney (Lisbie 70 mins). Subs: Grainger, Griffith, Rowlands, Omozusi.
Goals: MacDonald (26 & 48 mins), Lisbie (79 mins)
Bookings: Vincelot (65 mins), Cox (83 mins)
AFC Bournemouth: Jalal; Francis, Cook, Seaborne, Ritchie; Hughes; McQuoid, O’Kane, Fogden (Pitman 55 mins), Pugh (Fraser 85 mins); Grabban (Tubbs 74 mins). Subs: Allsop, Partington, MacDonald, Fletcher.
Goals: Pitman (66 mins)
Attendance: 5,136 (inc 1,407 Bournemouth fans)
Referee: James Linington