In windy conditions in Tauranga the sides were evenly matched for long spells, as Bay of Plenty pegged back their third-ranked visitors.
However, a penalty two minutes from time was enough to settle the issue in Northlands' favour as they snatched a victory that boosts their play-off chances.
It looked like the visitors were on course for a comfortable night when Sonatane Takulau scored a try in the third minute from seven phases, with Dan Hawkins converting and a penalty increasing the advantage to 10 points.
The Steamers were unable to get into the game until the 19th minute, but when Siaosi Longi converted from a line-out just outside the 22, they assumed the ascendancy.
They relentlessly brought the attack to Northland and were rewarded with another try by Joe Royal.
Northland"s Takulau responded in kind, weaving through the defensive gaps to put the ball across on his own, but there were worrying scenes for the visitors before half-time when Brook Gilmore was carried off on a stretcher following a mis-timed tackle.
Dan Hollinshead - who had an otherwise inspired night with the boot - missed a penalty from deep as Bay of Plenty went in behind.
The two sides traded penalties again after the interval, as Bay of Plenty began to build behind their powerful scrum.
Tim Bond was rewarded with a third score for the hosts, after Samisoni Fisilau had been denied by the TMO.
But Northland refused to roll over and after Warren Dunn had converted from captain Dan Pryor's good work with 13 minutes left, Ume Fosita kicked the decisive penalty to snatch victory.