Walker, 21, moves to Craven Park on a three-year deal and becomes the seventh new face in Craig Sandercock’s squad for 2013.
He said: “I didn’t know too much about the interest until last week. Craig (Sandercock) had seen me play in a few games at the start of last year and told me that he was impressed with what he’d seen. We then had a chat about the possibility of a move and I’m just glad to be here now.
“I obviously had time to think things over and in the end I feel that I made the right decision. Of course, it was tough leaving Huddersfield because I’ve been there a long time and know everyone but the staff and lads here at Hull KR have made me very welcome.
“Craig has told me how he sees me fitting into the squad and what he expects from me so I’m just looking forward to getting stuck into pre-season.”
The Bradford-born forward made four appearances for the Giants in 2012, and made his first Super League appearance against Salford back in April 2010.
He spent time on a dual-registration deal with Swinton in 2012, as well as a similar spell at Barrow the previous year.
Head Coach Sandercock added: “Adam fits the profile that we’re looking for in that he’s young, he’s English and he’s very keen to learn and improve as a player. I watched him a few times last season and was very impressed with what I saw.
“He has a lot of potential and if he works hard and maintains the right attitude then he has a great chance of establishing himself as a Super League player.”