Three games without defeat in May (W1, D2) gave Sunderland a shot at European football heading into the final day of the season, but only a win would be enough to leapfrog Chelsea and potentially snatch a spot.
Promising early runs from Cole Palmer and Enzo Le Fee each came to nothing, but the Black Cats soon took control of the contest, placing the visitors under sustained pressure.
And that eventually paid off in the 25th minute when the ball dropped kindly for Trai Hume, who prodded a first-time volley inside the near post from touch inside the box.
Now without a clean sheet in 16 league games, Chelsea looked for a response, but passed up a presentable opportunity before the break, as Joao Pedro guided a header off target.
Occupying a UEL spot thanks to half-time results elsewhere, Sunderland were 45 minutes from their best possible outcome, and they kept their foot on the gas after the restart, as Robert Sanchez was required to deny Brian Brobbey when one-on-one.
Yet within minutes, the hosts doubled their advantage in somewhat fortuitous circumstances as Brobbey swept a pull-back into Malo Gusto, who inadvertently turned the ball into his own net.
Chelsea needed a response, and they got one six minutes later when Palmer ended a 14-game goal drought for club and country by drilling a low effort past Robin Roefs.
But just as the Blues pulled themselves back into the contest, Wesley Fofana was dismissed for a second yellow card for hauling down Wilson Isidor.
Habib Diarra should have restored his side’s two-goal lead when he lifted over at the back post, but Sunderland ultimately dug deep to see out a famous win, capping off an outstanding season back in the top flight.
Just a second-ever victory in 17 season-ending Premier League matches (D3, L12) has huge ramifications for Sunderland, who end the season in seventh place and with European football to look forward to after going unbeaten in four (W2, D2).
For Chelsea, Calum McFarlane will now make way for the incoming Xabi Alonso, who will have no such European football to look forward to after a hugely disappointing 10th-placed finish for the current UEFA Conference League holders.
Flashscore Man of the Match: Trai Hume (Sunderland)
