The workhorse forward, 36, has been resigned and is flying to the UK tonight from Hungary.
He will train tomorrow and play against Glasgow Clan on Saturday.
Westerling was one of the players cleared out in a summer cull by former coach Paul Thompson.
But Mark Matheson was happy to see him accept an offer to re-join from Hungarian Erste Liga side Dunaujvarosi Acelbikak, where he has scored two goals and 10 points.
“I’m thrilled to be coming home to Sheffield” said Westerling. “I loved my time there and was delighted to know that the club wanted me back. I can’t wait to hook up with the guys tomorrow at the arena and see everyone at the game on Saturday. I’m so excited.”
Westerling will take the place of Ryan Martindale.
The Canadian is going home for family reasons - but the club has insisted that there is no suggestion of any bereavements or illnesses, as suggested in some quarters.
Matheson said: “When news came to me that Westy was available it was a no brainer."