Castleford have secured the second-row/centre on a two-year contract with a further two-year option.
Sutcliffe, 22, helped Leeds win the Challenge Cup at Wembley last year but has not had as many first-team opportunities this time around.
A switch to their West Yorkshire neighbours could be good for both parties and he said: “I can’t wait.
“I am really looking forward to it and I’m itching to get going
“I can’t wait to get in and meet all the lads and have a big 2022.
“I have always admired how Castleford play and love the fans there.
“I love how vocal they are, especially down at Cas with the fans being so close to the pitch because it is like having an extra man on the field. The fans are such a big part of it, for me.”
However, so is the potential impact of incoming Castleford coach Radford, the uncompromising former Hull FC and Bradford Bulls forward.
Sutcliffe said: “He obviously was a really good player.
“I like everything with the way he sets things out, so I can’t wait for him to take me under his wing and make me a physically tough player.
“Personally, I prefer the second-row position because you are more involved and more in the nitty gritty stuff.
“I don’t mind a bit of physicality. I pride my game on it especially in my defence, but I don’t mind playing either centre or back-row.”
Wakefield-born Sutcliffe came through the Rhinos academy having joined from Leeds amateur club Oulton Raiders.
“I have been with Leeds for eight years and have been privileged enough to win a Challenge Cup, so it’s been class,” he added.
“I owe a lot to them, and I have enjoyed my time.
“This season Cas have played a number of young players, and there is some really exciting talent coming through.
“I know Sam Hall and Brad Martin, who are young lads coming through and they look really good. It should be a good next few years for us.”
Radford admitted: “I’m surprised we had the opportunity to pick Alex up.
“He is a fantastic young player that can flip between second-row and centre, but I would love for him to nail down a second-row spot.
“I think he has all the physical attributes and the skillset to be able to play there. If you go at him, he’ll whack you because he’s got a shot on him as well.
“I am over the moon to have secured his services because there is a long-term future for him at Castleford Tigers. ”
Castleford have also signed Huddersfield Giants second-row Kenny Edwards on a season-long loan for 2022.