He's one of two goalkeepers signed by Mansfield this morning along with Scott Shearer who has joined them on a free transfer from Crewe.
But the 40-year-old Jensen, who left Burnley two years ago, will act as coach whilst also as back up to Shearer should it become necessary.
Manager Adam Murray said: "We've brought Brian in as a number two, but also as a goalkeeper coach. It's an area that I've been very mindful of over the past couple of years as we've never had a full time goalkeeper coach, so to be able to get a dual role for a package that I feel is right for the club and to bring someone in of Brian's stature and experience and intelligence football wise, is brilliant for us.
"It makes us very, very strong in that area now. Brian played at League One level last year and he's somebody that has played at the highest level. He's had a great career and comes here with a wealth of knowledge and experience and his contacts in the game are ridiculous.
"So to be able to bring him on board, both from a playing and coaching point of view, will be a major piece of the jigsaw. I feel we're in safe hands."
Jensen first came to England to join West Brom in and has gone on to make a total of 372 league appearances for them, Burnley, Bury and Crawley.