Popstar Anastacia and High School Musical choreographer Charles 'Chucky' Klapow will join the pair on the panel when the programme launches this summer, The Sun reports.
Don't Stop Believing - billed as Glee meets The X Factor - will follow the search for Britain's best musical performance group.
Speaking of the new signings, Five's head of entertainment Donna Taberer said: "Each judge will be a huge asset to our groups."
Earlier this month, it was claimed that stars of Glee could appear as guest panellists and mentors on the reality series depending on their filming schedules.
Former Spice Girl Emma Bunton is to host the programme.