Roberto Pereyra and Andre Gray's goals eased pressure on manager Javi Gracia as Watford ended a seven-match winless run by dispatching Newcastle 2-1.
Fit-again captain Troy Deeney missed a penalty, with Magpies keeper Martin Dubravka making a fine double save, while Ayoze Perez's impressive finish came to nought for the visitors.
The battling hosts threw their support behind boss Gracia's candidature to remain at the Hertfordshire helm next term, while Newcastle's season-ending malaise continues.
Former Malaga boss Gracia has already admitted he does not know whether he will still be Watford coach next season, given the Hornets' revolving door managerial policy.
Gracia only arrived in January, to become Watford's eighth manager in five years - but an 18-month contract carries precious little security.
The 48-year-old received a stirring show of support from his squad on Saturday however, as the Hornets held on for victory in their final Premier League home game of the season.
Pereyra's fifth goal of the season rubber stamped Watford's high-octane opening, the Argentina midfielder blasting home to cap a neat build-up.
The lively Will Hughes' astute angled ball bisected the Newcastle defence, before Pereyra blasted home in style.
The 27-year-old should have doubled his and his team's tally mere moments later, only for Dubravka to rescue the visitors.
Newcastle's Slovakia goalkeeper spared Rafael Benitez's blushes again when denying Gray who had raced clean through.
The former Burnley striker quickly atoned for that failed effort however, when Pereyra's fine hanging cross left him no option but to nod into the empty net.
Watford should have turned around three goals to the good, only for the inspired Dubravka to deny Deeney both from the penalty spot and the rebound.
Paul Dummett upended Gray in the box after an even foot race, only for Deeney to let the north east side off the hook.
When Newcastle finally produced a move of substance, after the break, they found the net.
The outstretched Perez expertly redirected Javier Manquillo's whipped cross for his sixth league goal of the campaign, immediately altering the game's complexion.
From armchair comfort to nail-gnawing nerves, suddenly Watford were back in a scrap.
Anonymous until the hour, Dwight Gayle then spurned two fine Newcastle chances, first unable to turn in the box, then failing to glance a header on target.
Perez flicked a corner the wrong side of the post as Newcastle continued to press, before Mikel Merino failed to convert a fine late chance.
Watford might have wilted in the bank holiday weekend heat, but still merited victory on a day when Newcastle paid dearly for being caught cold.