Tommy Makinson scored a first-half hat-trick for St Helens to ensure Hull's last-ditch bid for a Betfred Super League play-off place ended in failure.
Wigan's 26-8 victory over Castleford 24 hours earlier handed Hull one final chance to secure a top-five spot at the KCOM Stadium.
But they were not good enough to take advantage as high-flying Saints ran out comfortable 22-6 victors thanks to Makinson's treble and second-half scores for Mark Percival and Regan Grace.
It could have been a bigger winning margin but visiting full-back Lachlan Coote converted only one of his five shots at goal.
Saints' latest victory came three days after confirming former Tonga head coach Kristian Woolf would be the replacement for Justin Holbrook next season.
But Holbrook does not want to end his stint as a nearly man.
Beaten by Warrington in last season's play-off semi-finals, Saints, as hot favourites, also went down to their neighbours in last month's Challenge Cup final.
That defeat ended dreams of a domestic treble after finishing runaway winners of the League Leaders' Shield.
However, they are still in contention for further silverware this season - unlike Hull.
Last season a draw in this match would have been sufficient for the Black and Whites to leapfrog fifth-placed Castleford.
Instead, this year's introduction of golden point extra time after regulation 80 minutes meant only a win would be good enough.
At half-time and thanks to Makinson's treble, Hull trailed 14-6 and their hopes of a top-five spot fading fast.
Makinson swooped for his first touch down after nine minutes from full-back Coote's cut out pass.
He added his second six minutes later after Theo Fages floated a perfectly weighted kick to the corner.
And three was a magic number for the player and team when he accepted another Coote pass six minutes from the break to complete his hat-trick.
In between, prop Scott Taylor powered onto a Jamie Shaul pass to give Hull hope of a comeback.
And had Marc Sneyd clung on to his own kick with the try-line at his mercy it might have been a different story.
Despite that setback, Hull began the second half strongly and almost added a second try as Ratu Naulago tried desperately to reach Albert Kelly's kick.
Saints needed their best defence to keep the Black and Whites at bay.
And, having soaked up constant pressure, they broke away to leave Hull in deep trouble with a fourth try after 63 minutes from centre Percival.
Fortunately for the home side, Coote's wayward place kicking left them only two scores from drawing level.
But as desperation set in, Hull's last-ditch tactics failed to add the necessary points.
And it was game over when Grace put the finishing touches to Saints' win late on to ensure a season extension for grateful Castleford.