8th January 2019, 08:22 | Leeds
The 27-year-old Cumbrian was left without a club when his contract with Hull KR was not renewed at the end of the 2018 season.
But he was given the chance to train with the Rhinos and caught the eye of new coach David Furner in the club’s Boxing Day friendly against Wakefield Trinity.
“I am over the moon to have my contract situation all sorted,” said Donaldson, who was in the Rovers team that lost to the Rhinos in the 2015 Challenge Cup final at Wembley.
“It has been a tough few months for myself and my family but to have finally put pen to paper is a massive relief.
“It is a really big opportunity for myself and I am looking forward to continuing to work hard to earn my spot in the team.”