The pop band will join Christina Aguilera, Smokey Robinson, Cee Lo Green, Leona Lewis and Alien Ant Farm in performing at "Michael Forever - The Tribute Concert."
"We all owe Michael such a lot," said Peas frontman Will.i.am, who worked with Jackson before the pop star's death in July 2009.
He said Jackson's songs "have been an inspiration to my whole life and certainly formed the soundtrack to my childhood."
Oscar-winning actor and singer Jamie Foxx will serve as emcee for the Oct. 8 concert at Cardiff's Millennium Stadium.
The rock band KISS was dropped from the lineup last month amid protest from fans over comments made by singer-bassist Gene Simmons. In an interview shortly after Jackson died, Simmons spoke about his suspicions that the pop singer was a pedophile. Promoters said they were unaware of Simmons' statements when they booked KISS for the show, and rescinded the offer.
Jackson family members are split on their support for the concert, but Michael's mother, Katherine, said she will attend. Janet, Jermaine and Randy Jackson said they will not attend because it coincides with the involuntary manslaughter trial of Dr. Conrad Murray.