Swift, 19, has been given the number five shirt ahead of the upcoming Super League season, and is a product of the club’s academy system. He scored a hat-trick on his first team debut against Widnes in 2012.
He said: “I’m over the moon to sign a new contract at Saints. It’s a club I have always wanted to play for and I have enjoyed my time here so far.
“I know I have been given the number 5 shirt, but that isn’t a guarantee of a spot especially with the quality of the players we have here. I know I have to continue to work hard and keep learning.”
Prop Walmsley, 23, moved to Langtree Park from Batley ahead of last season, and went on to make 26 appearances. He had previously played for Great Britain students and the Dewsbury Celtic amateur club.
He said: “I’m delighted the club has rewarded me with a new contract and I would like to thank both Eamonn McManus and Mike Rush for showing faith in me. I am happy to commit my future to the club.
“I had a good season last year and now I am looking forward to getting stuck in and showing the fans the improvements I have made in pre-season.”
Head Coach Nathan Brown added: “Adam is a good young kid who took his chance last season. He is quick and eager to learn and I’m sure if he continues to develop will have a very good future in the game.
“Alex surprised everyone with how well he coped with the rigours of Super League but he thoroughly deserved the accolades that came his way. He adds a lot of size to our pack and like Adam will continue to develop and have a bright future.”