"2024 was really intense. I've done a lot of big competitions and I'm exhausted," the 22-year-old Frenchman said in post on Instagram.
"It's time for me to step back, train hard and start preparing future challenges."
Marchand won five medals at the Paris Olympics, four of which were gold, and then participated in the three stages of the Short Course World Cup in Asia.
He won the three distances of the medley -- 100m, 200m and 400m -- in Shanghai, Incheon and Singapore, where he broke the world record in the 200m medley on November 1, ideal preparation for worlds in Budapest from December 10-15.
His last appearance in competition was on November 10 when he represented his club Toulouse at the Interclubs in Montauban, southwestern France.
