Arsenal’s record goalscorer had rejoined the club he left for Barcelona in 2007 on a short-term loan deal from New York Red Bulls and did not disappoint when he slotted home on 78 minutes to finally break the resistance of the npower Championship club.
Henry, 34, is available for a six-week spell which will take in matches against Manchester United, AC Milan in the Champions League and possibly even the showdown with arch-rivals Tottenham on February 26.
And given Monday night’s 20-minute cameo masterclass, that could just be the spark Arsenal need to push on towards a successful end to a season which started so badly.
The Gunners, who rested current captain Robin van Persie, started strongly.
Andrey Arshavin was set up by Marouane Chamakh, who was set to leave for the African Nations Cup with Morocco after the game, but the Russian blasted over from edge of box.
Arsenal pressed for long spells as Leeds were pushed deeper and deeper, but they lacked any real spark in the final third.
Sebastien Squillaci headed wide at the far post when Mikel Arteta, captain for the evening, whipped over a free-kick from the right.
At least on-loan Tottenham winger Andros Townsend was showing some endeavour for the visitors as he made some progress down the left flank, but he lacked support in the middle.
On 15 minutes, Aaron Ramsey bolted to the edge of the Leeds penalty area and drove a rising shot just over the angle.
The Wales captain then saw his 12-yard effort deflected over following another mazy run by Arshavin.