Fitzpatrick, 29, joins Thunder from Leeds based Yorkshire Carnegie and will be immediately available for selection, with a potential debut coming against the University of Gloucestershire All Golds on Sunday July 24.
Recognised in his Falcons days as a strong and direct runner, Fitzpatrick was highly regarded during his union career for his ability to burst through defences and hard hitting tackles; attributes that he will look to bring to bear for Thunder in the second row.
The Sheildsman made 89 appearances for the Falcons and Carnegie across a six year career and was persuaded to play rugby league by Thunder head coach Mick Mantelli, after Newcastle Rugby chairman Semore Kurdi suggested the idea earlier in this season.
Having trained with the squad in recent weeks under the watchful gaze of the Australian, Mantelli is keen to see what he can do.
Thunder’s head coach said: “Fitzy has been training with us for a couple of weeks now and has been going well in those sessions. He’s a big and powerful lad and it will be good to see him bring what he was known for in union to our team.
“We’ve got six big games coming up with the chance of a trophy at the end of that if we play to our potential and Fitzy can have a big role to play in that.”
Fitzpatrick’s signing further strengthens the North Eastern contingent in the Thunder squad, with 12 of the 25 man squad now hailing from the region.