City are in the midst of a four-team scrap for automatic promotion and, with two of their rivals winning, needed something special at Elland Road, especially as Graham Dorrans had already missed a penalty.
Howson, who made 226 appearances for Leeds and captained them to promotion, provided it in the 58th minute, with his cool edge-of-the-box finish paving the way for a 2-0 win. Dorrans added a late clincher.
Consequently Norwich are second with three games left, although a big win for Watford against Nottingham Forest on Wednesday could change that.
It was perhaps inevitable that Howson would be the game’s key man, returning to Elland Road for the first time since leaving with a heavy heart in January 2012.
He was involved in the game’s first talking point 30 minutes in, winning Norwich the penalty that Dorrans would miss.
He got a jump on Liam Cooper into the Leeds area and the home skipper was unable to cover his run, so ended up bundling him over, which caused Mike Jones to point to the spot.
Dorrans assumed duties, but after a forceful run-up slammed his kick against the bar and with it went the best chance.
The same man had the next opportunity too, but was again too heavy-footed as he ran on to a Cameron Jerome cut-back, driving over.
For their part Leeds were willing, but were unable to get a sight of John Ruddy’s goal and when they did, in the 48th minute, Sol Bamba headed wide from a corner.
The best chances continued to fall to Norwich, with Russ Martin getting space in the area only to see his curled effort beaten away by Marco Silvestri, crucially away from the oncoming traffic.
Alex Tettey also saw a 20-yard fizzer go just over and in the 58th minute the opener arrived.
Nathan Redmond was given space on the left, he came in and rolled a ball across to Howson, who, with plenty of time, picked his spot and prodded a cute finish beyond Silvestri.
Norwich fans taunted their opposition with chants of ‘he’s one of your own’, while Leeds supporters applauded Howson for refusing to celebrate.
Leeds responded with Scott Wootton cutting in and shooting, but Ruddy denied him, with the goalkeeper doing so more spectacularly to frustrate Alex Mowatt in the dying minutes.
The midfielder’s long-ranger was going in until Ruddy clawed it out from inside his right-hand post.
Instead, Dorrans drilled in a last-minute second after Jerome robbed Gaetano Berardi to seal the points for Norwich.