The former Leeds Rhinos player, 24, has struggled for game-time at Belle Vue and not played for Trinity this term.
However, the ex-Bradford Bulls, Halifax and Featherstone Rovers prop has plenty of experience and is looking to make the most of his chance with the Championship high-fliers.
“Jordan will add size and physicality to our forward pack,” said York coach James Ford.
“He’s a player we tried signing in the off-season and I’m delighted the club - and specifically ‘squadbuilder’ - have backed us on this acquisition.
“I’m confident that if Jordan buys into our culture and attitude towards hard work he’ll kick on and fulfil his potential.”
Leeds-born Baldwinson was highly-rated as a youngster having come through the Rhinos academy ranks and was signed by New Zealand Warriors while still a teenager although he never played an NRL game.
Able to play prop or back-row, he won Championship Young Player of the Year with Featherstone in 2015 and then joined Rhinos before moving onto Wakefield.
“I’m really looking forward to getting started at York,” said Baldwinson, who spent time on loan at Leigh Centurions last term and could debut in Saturday night’s Challenge Cup game at Widnes Vikings.
“With the lads there, there is a huge buzz about the Knights this year.
“Looking at what they have done already this season and where they stand in the table is a credit to the boys and their coach.
“I’m really hoping I can add to what is already a good squad and help secure more wins with some real tough fixtures ahead.”