The 23-year-old could make his Wakefield debut against Toulouse Olympique in the south of France on Saturday.
Butler made his Super League breakthrough with London Broncos before joining Warrington at the end of 2020.
He found game time hard to come by at the Halliwell Jones Stadium with the front-rower featuring just once this season.
Butler, who has appeared on the international stage with England Knights, is relishing the chance to get his career back on track with Trinity.
“I’m now looking forward to kicking on at Wakefield, finding some form and playing regular rugby," he said.
"I’ve played with a few of the boys at London and Warrington and they’re all good people so it’s nice to see some familiar faces too.
"I know from playing against Wakefield that they are a real tough team to play against.
"Hopefully I can add something to the squad and help us get back to the form showed a few weeks ago.”
The signing of Butler bolsters Wakefield's pack ahead of this weekend's crunch clash with Toulouse.
Wakefield are only four points better off than the French side after losing four games in a row.
Trinity head coach Willie Poching said: “We’re delighted to be able to bring Rob to Wakefield Trinity.
"He’s young, English and a man of significant size which is of real value for us at this moment of time.
“I know he will add to the quality of the group with the person that he is and the player that he is.
"We look forward to helping this young front-rower blossom and grow and hopefully find his feet in Super League.
“He also adds to the competition already here within our front-row stocks and that can only be a positive for us.”
In other transfer news, Castleford Tigers winger Sosaia Feki will step up his recovery from his latest injury during a two-week loan spell with Featherstone Rovers.
Feki, who has featured only once for the Tigers since his arrival at the start of 2020, could make his Featherstone debut against Dewsbury Rams on Sunday.