Jersey survived a spirited second-half display from Doncaster to secure their first win in more than two months.
The islanders led 23-9 at half-time following tries from prop Harry Williams and centre Drew Locke.
But the Knights, searching for their first league win since September, were more industrious after the break and pulled a try back through Tomasi Palu.
Despite finishing with 14 men after Jonny Bentley's yellow card, the visitors held on for the win.
The out-of-form sides had gone into the game occupying 10th and 11th spots in the table, with Jersey two points above the Yorkshire outfit.
Doncaster started the brighter of the two teams and dealt with the cold conditions better early on to lead 3-0 through Dougie Flockhart's early penalty.
But the first-half tries both went Jersey's way, as they hit back when Williams crashed over from a maul and then Locke raced onto Mark McCrea's kick to score by the posts.
The hosts were quickest and sharpest out of the blocks in the second period and deserved to narrow the gap when Tongan scrum-half Palu touched down after his quickly-taken penalty just before the hour mark.
At the other end, fly-half Bentley made no mistake with a penalty to re-establish the Channel Islands side's 10-point advantage, but he was to end the game in the sin bin for killing the ball at the ruck.
Flockhart's penalty narrowed the deficit to seven points, but Jersey's 14 men held on to ensure there was no late equalising try.
The Knights remain in 11th spot, while Jersey's first win since 8 November lifts them to eighth in the table.
Jersey: Grant Pointer, Mark Foster, Drew Locke, Lewis Robling, Mark McCrea, Jonny Bentley, Samisoni Fisilau; Sam Lockwood, Joe Buckle, Harry Williams, Pierce Phillips, Nick Campbell, Michael Noone, Ryan Hodson (capt), Nick Haining.
Replacements: Nick Selway, Ignacio Lancuba, Danny Herriott, Dave Markham, Paula Kaho, Ryan Glynn, Aaron Penberthy.
Doncaster: Paul Jarvis, Dougie Flockhart, George Catchpole, Bevon Armitage, Tyson Lewis, Paul Roberts, Tomasi Palu; Richard List, Harry Thacker, Colin Quigley, Matthew Challinor, Jon Phelan, Laurence Pearce, Michael Hills (capt), Alex Shaw
Replacements: Jack Bergmanas, Ben Hunter, Ross Davies, Tyler Hotson, Latu Makaafi, Piers Francis, Bruno Bravo.