Ashurst, 24, joins Hull KR’s Craig Hall and Catalan Dragons’ Mickael Simon in James Webster’s recruitment so far.
He has scored four tries in 17 games for Salford this season having initially come through the ranks at St Helens.
“I’m excited for a new challenge,” said the player, who scored 10 tries in 59 games over three years for Saints before switching to their Super League rivals in 2011.
“Webbo really sold the club to me and the work ethic that is in place there and I’m just looking to come and work hard and do my bit for the squad.
“I suppose the next step for me is to take on a bit more of a senior role but I’m still quite young and know I’ve got improvement in me so I’m just aiming to play a regular part for the team and do my bit.
“Every year teams are aiming for that top eight and even more so next season with the new structure. Everyone will be wanting to achieve the same thing and I believe if we play to our potential then we have got a very good chance.
“I spoke to (Trinity’s on-loan Salford scrum-half) Tim Smith and he had good things to say about Wakefield.
“He’s really enjoying it and says it’s a good environment to be a part of so I’m looking forward to joining that.”
Webster said: “Matt has had a great education having come through at St. Helens and has played really well at Salford.
“He’s an extremely athletic and versatile player that can play both on the edge and in the middle.
“With Matt we have signed another young, promising British player that we think we can add plenty to our squad, especially with the ball.”