Liverpool skipper Steven Gerrard's dreadful error handed Arsenal a victory which keeps alive their hopes of a Champions League spot for next season.
Henry celebrates his late winner
Seconds after Xabi Alonso's dismissal, Gerrard's back pass was intercepted by Thierry Henry, who rounded Jose Reina for his second goal.
Henry's exquisite finish had given Arsenal a first-half lead.
Luis Garcia levelled for Liverpool after Jens Lehmann could only parry Gerrard's thumping shot.
As expected in a game of high-calibre football, Arsenal took the lead through a superbly crafted goal.
Cesc Fabregas waited patiently on Henry's run and threaded the needle with his pass between Steve Finnan and Jamie Carragher for Henry to collect and run on to curl a shot around Reina.
While Henry again proved himself the consummate goalscorer, Peter Crouch summed up Liverpool's woes in front of goal.
Finnan picked out the unmarked Crouch perfectly with his inviting cross, but from eight yards out the England striker headed wide.
Liverpool made a determined start to the second half as they pressed Arsenal high up the pitch.
But they left themselves prone to Arsenal's pace on the break and, as the Gunners picked them apart at pace, Henry again found himself with only Reina to beat but this time he curled his shot inches wide.
Henry surprisingly spurned another chance to wrap up the points when Aleksandr Hleb's pass picked out the Frenchman but Reina spread himself to save the shot.
High jinks as Henry and Luis Garcia challenge for the ball
Liverpool worked hard and passed the ball well to get themselves back in the game but their lack of conviction and cutting edge in the last third left Lehmann largely untroubled.
But the big German keeper was at fault as Liverpool carved out an equaliser.
Arsenal were looking for a foul as Fabregas was roughed out of possession but the ball broke for Gerrard whose powerful shot was not dealt with properly by Lehmann.
The Arsenal keeper parried the ball into the air and Garcia reacted first to head the loose ball home.
Liverpool looked set to finish the stronger and Lehmann was relieved as Garcia's fearsome volley was partially blocked by Phillipe Senderos.
But their world fell apart in the space of a couple of minutes. First Alonso was sent off for a second yellow card, and seconds later, Gerrard's back pass laid the ball on a plate for Henry who rounded Reina to score.
Henry teed up Robert Pires as Arsenal looked to round off their win in style but he hit the post.
Arsenal: Lehmann, Eboue, Toure, Senderos, Flamini, Hleb, Fabregas, Silva, Ljungberg (Pires 15), Adebayor (Bergkamp 67), Henry.
Subs Not Used: Almunia, Song Billong, Djourou.
Goals: Henry 21, 83.
Liverpool: Reina, Finnan, Carragher, Hyypia, Warnock, Kromkamp (Kewell 45), Hamann (Fowler 73), Alonso, Luis Garcia, Gerrard, Crouch.
Subs Not Used: Dudek, Morientes, Traore.
Sent Off: Alonso (81).
Booked: Alonso, Luis Garcia.
Goals: Luis Garcia 76.
Ref: S Bennett (Kent).