The England talisman set aside all thoughts of his summer move to France to drag Saracens away from the Chiefs – even finding time to tee up Theo McFarland’s last-play try with a deft crossfield chip.
Saracens finally delivered the ominous play-offs warning that they had been seeking for some time, running in five tries and edging away after a tense first 50 minutes.
Hooker James Hadfield crossed twice, with Ivan Van Zyl and Juan Martin Gonzalez adding to McFarland’s added-time effort.
Farrell booted 15 points to add to Sarries’ tries, and secure a vital victory as the Men In Black seek to time their run perfectly in the quest for a seventh Premiership crown.
With the game finely poised at 22-22 and almost 30 minutes left, Farrell booted two quick goals – one off the tee and one off the turf – to drag Sarries clear.
Hooker Hadfield then crashed over for his second score of the night, and Saracens never once looked back afterwards.
The try bonus-point proved as crucial as the win at a freezing StoneX Stadium for an eventually hot Saracens.
The Men in Black jumped from seventh to fourth courtesy of this win, leapfrogging Exeter en route to the play-off berths.
Sale can push Saracens back out of the play-off places with a win at Gloucester tomorrow.
But Mark McCall’s men will head into the seven-week Premiership break for the Six Nations safe in the knowledge that their title defence is still alive and kicking.
The reigning champions want a seventh league crown this summer, to send Farrell off to Racing 92 in a blaze of glory.
Their piecemeal form of late had threatened to derail that quest, with Saracens having already lost five league games this season.
But now Saracens can head into this lengthy break knowing full well that once the business end of the season arrives, they will return with all their top stars – and fully focused on claiming yet more league glory.
Sarries opened the night with a blitzkrieg driving-maul try, with hooker Hadfield rising last with the ball for the score.
Woodburn hit back to level the try count for the Chiefs, only for Van Zyl to rush onto Andy Christie’s pop off the deck for the hosts.
Fisilau bundled in from a short lineout as the Chiefs caught Sarries cold, with Josh Hodge taking over kicking duties and landing a belter of a penalty.
That meant the teams turned around at 15-15, with Sarries made to sweat in a match littered with mistakes from both sides.
More errors after the break – this time from Exeter – led to the next score, with Gonzalez landing on a loose ball to dot down after miscalculations from both Hodge and Stuart Townsend.
Saracens had hoped that gift of a score would be the ideal way for them to start looking to wrap up some kind of dominance.
Instead, Hodge raced clear after Christie’s hopeful deep punt, cruising past Farrell en route to sparking the try of the night.
Woodburn and Townsend then combined to send lock forward Tuima cantering across the whitewash, to cap a genuine field-length score.
Hodge’s conversion had the game tied again at 22-22 heading into the final half hour.
Farrell edged Sarries ahead with a nerveless penalty, before the skipper slotted a 40-metre drop-goal, to push that newfound lead to six points.
Then McFarland powered down the right wing, recycled at pace – and Hadfield bundled in for his second and Saracens’ fourth score.
Farrell still found time to chip into the corner for McFarland’s try at the death, wrapping up a crucial win to send the north Londoners into the lengthy break finally in fine spirits.