West Ham will release Danny Ings, Lukasz Fabianski, Vladimir Coufal and Aaron Cresswell when their contracts expires at the end of the season.
Hammers boss Graham Potter has opted to allow the quartet to move on as he begins to overhaul the struggling Premier League side.
Left-back Cresswell has spent 11 seasons with West Ham, and holds a club record for the longest unbroken stint as a top-flight player.
The 35-year-old and goalkeeper Fabianski, right-back Coufal and striker Ings were all members of the squad which won the Uefa Conference League in 2023.
"Aaron, Lukasz, Vladimir and Danny have been a pleasure to work with in my time here so far," Potter told reporters on Friday.
"They are all brilliant professionals on and off the pitch, with fantastic experience in the Premier League, and clearly loved and admired by their teammates and everyone here at the club.
"We felt it was important to confirm this news now, out of respect for them and the service they have given to the club, and to allow our supporters to show their appreciation at our final home match of the season."
Potter is yet to decide on the future of West Ham striker Michail Antonio, who has been sidelined since suffering a broken leg in a horror car crash in December.
The 34-year-old, who will also be out of contract at the end of the season, is now taking part in light training with his teammates.
"When we have something to announce we will announce it. I think he's in a unique situation in terms of how he's recovering from his injuries," said Potter, whose fourth-bottom side travel to Manchester United on Sunday.