The midfielder, a free agent after leaving Burnley this summer, will meet up with his new team-mates at their York training camp this weekend once the paperwork on his deal is completed.
Hendrick, 28, is seen as a “like-for-like” replacement for former loanee Nabil Bentaleb, who won’t be returning to St James’s Park.
Speaking to the Gazette, head coach Bruce said: “We hope that he can join us on Sunday. He has to go through all the tests and the Covid stuff. We hope we can get him over the weekend.”
Bentaleb, 25, spent the second half of last season on loan at Newcastle from Schalke 04. Bruce said: "With Nabil going back, and the sort of money that Nabil was going to be at, I thought maybe Jeff Hendrick was a better bet with his experience and know-how in the Premier League.”