The former heavyweight World champion returns to the ring in 10 days at the O2 Arena but appeared in a relaxed mood at the star-studded bash.
The 36-year-old mixed with former England and Arsenal star Sol Campbell, magician Dynamo, vlogger Zanna Van Dijk and fashion entrepreneur Xenia at the Roundhouse in London.
The event included a carousel, a ball pond, circus artists and street magic from Dynamo himself.
The Liverpudlian is moving up from cruiserweight to take on Haye, who made the same move earlier in his career.
“You want the biggest possible fight — me and Joshua is the biggest for us both,” he told The Sun . “We could sell out Wembley Stadium twice over.”
The card on March 4 will also feature Welsh star and IBF World featherweight champion Lee Selby against Spaniard Andoni Gago.