An £11.4 million ($14.8 million, 12.5 million euros) capture from Montpellier, French striker Mounie struck twice after Joel Ward’s 23rd-minute own goal had broken the deadlock.
It was Huddersfield’s first top-flight game since 1972 and it finished with their first top-flight win since 1971 as David Wagner’s men made a dream start to life back among the elite.
Huddersfield are only the fourth promoted team to have won their opening Premier League match since 2008.
While Huddersfield’s travelling fans rejoiced, Palace’s supporters were left to reflect on a false dawn in what was Frank de Boer’s first competitive game since succeeding Sam Allardyce as manager.
Huddersfield manager Wagner awarded debuts to four new players, but there was no sign of unfamiliarity in their ranks as they tore into Palace from the off at Selhurst Park.
They created their first chance in the second minute, Tom Ince side-footing straight at Palace goalkeeper Wayne Hennessey after Patrick van Aanholt had inadvertently headed Tommy Smith’s cross into his path.
The visitors went ahead when Aaron Mooy’s corner was flicked on by Christopher Schindler for Mathias Jorgenson, whose header struck Ward’s knee and bounced in for an own goal.
Within three minutes it was 2-0 as Mounie opened his Huddersfield account with a header from Mooy’s cross.
Jorgensen went close with a header and when Palace finally procured a sight of goal, Wilfried Zaha dragged wide after breaking into the box.
Palace finally began to assert themselves in the second half and Huddersfield’s debutant goalkeeper Jonas Lossl was obliged to save smartly from Christian Benteke and Zaha in rapid succession.
But Huddersfield held firm and completed a fairytale return to top flight football in the 79th minute when Mounie smashed in his second goal from Colin Quaner’s pass.
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