The 22-year-old becomes the ninth Red Devil to spent this campaign away from Old Trafford following the departures of Chris Smalling and Alexis Sanchez.
It is the fourth loan of Borthwick-Jackson's career so far, following underwhelming spells at Wolves, Leeds and Scunthorpe.
“I'm delighted and I can't wait to get started," he told Tranmere's website after agreeing a temporary switch to Prenton Park.
“I think it's a case of me getting back to my best and showcasing what I can do to help Tranmere finish as high up the league table as possible.
“The manager was keen, and he wanted me. I'm looking forward to working with him and that's half the battle to have a manager like that. He said he knows my quality and he wants me to get back enjoying my football."