The talented centre, 21, was called up to Shaun Wane’s England squad earlier this year and is one of the most highly-rated young players in Betfred Super League.
Tying him down to a long-term contract has been one of Leeds’ most important pieces of business and Agar is understandably pleased given the amount of interest in the player’s services.
He said: “Harry is an exceptional talent. He is highly motivated and highly ambitious.
“Harry sets the bar very high for himself and we feel he has the potential to scale the summits of our sport.”
Newman, who was due to be out of contract at the end of 2022, has bounced back from a serious double-leg fracture suffered last year and his eyes are set firmly on a World Cup place next autumn. Agar added: “It’s fair to say he’s been one of the most sought-after players in both codes of world rugby so to secure him on a long-term deal is great news for the Rhinos and Harry.
“There is still lots of development in him. His rise has been rapid but we all believe there is still huge potential for Harry to grow.”