Burnley beating Wolves and Southampton’s victory at Brighton left Huddersfield requiring a point to remain in contention for survival but they could not manage it at Selhurst Park.
Recalled midfield man Jonathan Hogg admitted: “I’m devastated. It’s not good. On a personal level, I’m devastated because of all the hard work that’s gone in to get us where we are today; it’s all been taken away from us.
“It’s been enjoyable while we’ve been in the Premier League but we need to make sure we put things right and try our best to bounce back.”
Goals from Luka Milivojevic and Patrick van Aanholt confirmed the drop which has been looming for a long time but Hogg said: “I think the fans have been fantastic and we need to try and give them something to cheer about because they’ve stuck by us through thick and thin.
“We need to make sure we make them proud and at least get a couple more wins for them.”
“We need to try our best to be positive. It’ll be hard over the next three or four days to get our heads round it, but we need to stay focused and keep looking ahead.”
Huddersfield have become just the second Premier League team – after Derby County in 2008 – to be relegated before the end of March.
From 32 league fixtures, they have taken only 14 points, leaving them 19 from safety, something even 14th-placed Palace are yet to achieve.
Town head coach Jan Siewert had made three changes to his team, replacing Jonas Lossl, Jon Stankovic and Aaron Rowe with Ben Hamer, Christopher Schindler and Hogg, and was rewarded with an encouraging start.
While his team rarely looked like scoring, they occasionally stretched their hosts, who even with the influential Wilfried Zaha fit again were regularly denied in the final third.
But when Zaha was brought down in the area by Juninho Bacuna, referee Lee Probert had little choice but to award the 76th-minute penalty that essentially consigned the visitors to relegation. The reliable Milivojevic confidently finished down the middle as Hamer dived, giving Palace the lead.
Zaha went close again and Palace took until the 88th minute to double their lead. This time Zaha sent Van Aanholt clear and watched as the full-back shot at an angle past Hamer and into the back of the net, confirming Huddersfield’s return to the Championship.
Crystal Palace: Guaita, Wan Bissaka, Tomkins, Dann, Van Aanholt, Meyer (McArthur 46), Milivojevic, Schlupp, Townsend (Kouyate 80), Batshuayi (Benteke 73), Zaha. Unused substitutes: Ward, Hennessey, Ayew, Kelly.
Huddersfield Town: Hamer, Smith, Schindler, Kongolo, Durm, Bacuna (Williams 80), Hogg, Mooy, Pritchard (Stankovic 90), Lowe (Kachunga 80), Ahearne-Grant. Unused substitutes: Coleman, Hadergjonaj, Daly, Rowe.
Referee: L Probert (Wiltshire).