The English pair have each put pen to paper on five-fight deals, which will commit them exclusively to the promotion for the next 18 months.
Newman (5-1), who alternates between American Top Team and London’s Team Titan, is one of the UK’s top lightweight prospects, having taken all five of his wins to date via first-round stoppage.
Still only 23, Newman featured as a welterweight on The Smashes series of The Ultimate Fighter last year and joins Team UK colleagues Valentino Petrescu and Bola Omoyele on the CWFC roster.
Barnes (12-10-0-1nc), who will feature at Cage Warriors 57 in Liverpool on July 20, is ranked as one of the UK’s top 15 middleweights.
The charismatic 28-year-old, who hails from Blackpool, spent four years as part of the Wolfslair Academy and has taken all 12 of his career wins by stoppage, 10 of which have come via submission.
“We’re always willing to provide a platform for talented fighters who want to compete regularly so it’s great to have Luke and Leeroy on board,” said Cage Warriors CEO Graham Boylan.
“They both have the skills and the right attitude, they want to be active so I know they’ll fit right in at Cage Warriors. I wish both guys luck and I’m looking forward to seeing them in action.”