In a topsy-turvy encounter that saw the lead change hands seven times, Widnes had the decisive say with two tries in the final 16 minutes.
That was tough on Rovers, who showed a fight sadly absent in the home defeat by Batley seven days earlier to give the Vikings a serious examination.
It was a solid effort from the visitors, unfortunately let down by some needless and avoidable errors but with enough grit and determination to satisfy even the most critical of fans.
And although they now appear unlikely to sneak into sixth - Widnes now have a three-point buffer and Sheffield are two points ahead - a creditable seventh-place finish is still a realistic possibility, providing Rovers can win their last two - at Dewsbury on Sunday and at home to Halifax seven days later.
A penalty from Stuart Dickens broke the deadlock on nine minutes. Widnes turned down a chance to level to run a penalty and initially it looked to have back-fired as they spilled possession but when Rovers did likewise from the subsequent set Jim Gannon's off-load put hooker Bob Beswick in for a try that Steve Tyrer goaled.
With Andy Kain (flu) and Tommy Haughey (knee) left out, Featherstone were forced into changes. James Houston and Richard Blakeway came straight back in after missing a game suspended and Paul Handforth was restored to half-back in place of Kain, with Jack Lee going to hooker.
And it was on-loan utility Lee who provided the pass that enabled substitute Tony Tonks to cross with his first touch, a try that Handforth goaled.
Back came Widnes after the restart was allowed to bounce dead - it was that kind of game - and moments later Beswick twisted in a tackle to put Ian Hardman over on 25 minutes, with Tyrer again on target.
On-loan half-back Anthony Thackeray, strongly linked with a switch from Cas to Widnes next season, was not doing his chances of a move any harm against his prospective employers and swooped on a chip from Andy Kirk to go close.
Rovers regained the lead on the half-hour when Loz Wildbore dummied his way through and beat Hardman for a try that Handforth converted for a 14-12 interval lead.
Pressure
After defending strongly to absorb early second-half pressure, Rovers crumbled to fall behind on 49 minutes when loose-forward Lee Paterson punished some tame defence for the home side's third six-pointer.
The lead lasted six minutes, with the impressive Wildbore again charging on to a Lee pass and set up a try in the corner for winger Waine Pryce. Dickens' fine goal from wide out nudged Rovers 20-18 ahead.
It was to be their final points, however, as Widnes capitalised on successive sets to score next, a 66th-minute try from scrum-half Matty Smith set up by ex-Cas Tigers and Whitehaven back-row Richard Fletcher.
A knock-on in good position let Widnes off the hook after a good chase earned Featherstone a drop-out and just before the end home substitute Sam Barlow was allowed to stroll through a leaden defence to complete a scoreline that flattered the home team.