The Knights have signed Jack Roberts as the second arrival ahead of the 2019/20 season.
The centre will join from Cardiff Blues in the summer after spending two seasons at the Welsh club.
The 27-year-old has Premiership experience with Leicester Tigers as he spent three seasons;making 36 appearances during his time at Welford Road.
The Welshman started his career at the Scarlets academy before moving to Llandovery and then to Championship side Rotherham Titans. Jack spent one season at the South Yorkshire side, making 29 appearances in all competitions and showed his talents and attributes that lead him to the Premiership with a move to Leicester Tigers in 2014.
Most recently, the Welshman has played for Cardiff RFC as they challenge for the Principality Premiership.
DoR Clive Griffiths was pleased to make the second signing of the 2019/20 season.
“Jack is maybe more well known to our neighbours Rotherham for which he played for before moving to Leicester Tigers and then Cardiff Blues.
He has struggled with injury and is now working his way back, but having watched his games I had no hesitation to add him to our squad.
He will add an good attacking and defence style of rugby to the Knights play.”
Jack praised the ambition of the club in his decision to switch back to the Championship.
“I’m really looking forward to joining Doncaster next year. I’m excited by the potential of this Doncaster squad. I have good friends there and they’ve always spoken very highly of the club and culture that’s been built.
I can’t wait to get started and test myself in the Championship again.”