"Having worked with him on a number of occasions, his great talent always shone through and his self deprecating sense of humour made the experience even more pleasurable."
In 2005, Michael joined McCartney onstage during the bassist's Live 8 concert at London's Hyde Park to perform "Drive My Car."
The two singers also collaborated on a new version of "Heal the Pain," a Listen Without Prejudice track that the duo rerecorded for Michael's 2006 career-spanning greatest hits collection Twenty Five.
Queen's Brian May also remembered Michael in a post on the guitarist's site; Michael performing alongside Queen during the legendary Freddie Mercury Tribute Concert at London's Wembley Stadium in April 1992.
"I just saw the sad news about George Michael as I was heading for bed. I don’t have the words," May wrote. "This year has cruelly taken so many fine people way too young. And George? That gentle boy? All that beautiful talent? Can't begin to compute this. RIP George. Sing with Freddie. And the Angels."
Michael's rendition of "Somebody to Love" with Queen was among the highlights of that all-star 1992 concert.
Michael died of heart failure Sunday at his home in Goring in Oxfordshire, England. "It is with great sadness that we can confirm our beloved son, brother and friend George passed away peacefully at home over the Christmas period," his rep said in a statement. "The family would ask that their privacy be respected at this difficult and emotional time. There will be no further comment at this stage."