The 24-year-old forward, who can operate at prop or loose forward, made his senior debut for Hull FC in 2022 and has since made 32 appearances for the Airlie Birds.
Gardiner also gained further experience in the Betfred Championship during the 2025 campaign, enjoying loan spells with Doncaster RLFC and Featherstone Rovers.
Gardiner expressed his excitement at joining the Bulls and his desire to make an impact in a new environment.
“I’m buzzing to have signed for such a great club. I can’t wait to pull the jersey on and get in front of the fans – they’re a really loyal group,” he said.
“It’s a massive club with a rich history and a strong fan base, and that really attracted me to the Bulls.
“After speaking with Kurt and hearing about how he wants to play, I felt it really suits my game. I like to think I’m a hard-working player who does the tough stuff, brings physicality, and can play big minutes. I’m still young and have a lot to improve on, but I’m hungry to kick on and establish myself at Super League level.
“I had a tough year with injuries at Hull, so a fresh start at Bradford feels right. Everyone knows what the Bulls have achieved in the past, and hopefully we can bring some of those great times back.”
Head Coach Kurt Haggerty believes Gardiner is a player with significant untapped potential.
“Will has very much gone under the radar at Hull,” said Haggerty. “He’s had a good year, he’s big, he’s English, and he’s a young front-rower with plenty of development ahead of him. There’s a lot of work we can do together, and I believe there’s a very good Super League player in there.”