Their first win in eight Premier League games lifted them up to 16th in the table, one point and a place behind Huddersfield, who slipped to another damaging home league defeat - their sixth of the season.
Goals in each half from James Tomkins and Luka Milivojevic secured a fully-merited victory for Roy Hodgson's Eagles, who outplayed their opponents for the majority of the game to send them off into the global break in good spirits.
The return of Wilfried Zaha to the Palace starting line-up after over a month out with injury not surprisingly had a positive impact.
Tomkins should have had his second of the encounter not long after either, only for the defender to see his shot cleared off the line by Mounie, following yet more poor defending from a corner.
Palace were full value for the victory having taken the lead in the 23rd minute through James Tomkins before skipper Luka Milivojevic's 68th-minute penalty secured the win.
Zaha, withdrawn in the 89th minute, had missed Palace's previous four games, which all ended in defeat.
Huddersfield looked to respond immediately.
The opener seemed to spark a lacklustre Town into life and it was Collin Quaner who made good progress down the right wing, although his clever cut-back for Alex Pritchard was quashed following some standout defensive work from Milivojevic just inside his own box.
David Wagner replaced left-back Scott Malone with Chris Lowe at the interval and Rajiv van La Parra went on for Ince soon after as Huddersfield struggled to build momentum.
The lead came from a corner from early substitute Yohan Cabaye with Huddersfield's defence failing to clear and Tomkins poking home at the second attempt.
James McArthur headed Aaron Wan-Bissaka's cross just wide and Cabaye forced Lossl to save his low effort.
Palace were full value for the win, too, to leave Town needing to find a response when the Premier League resumes after the global break with an Easter Saturday trip to Newcastle United.