Willis, 24, returns to the club for a second spell and has signed on a three-month loan.
He said: “Gainsborough is a club, full of good people that I have a lot of respect for. I am delighted to be here and playing football again.
“Gainsborough is somewhere I know and enjoy playing my football at, I am just buzzing to get back playing again. I spoke to Kingy a bit and it’s good to know he wants me.
“The club wants me and it’s a good place to be. Obviously we want to be higher in the league, that’s got to be the priority at the moment. We need to start getting some points on the board and of course, clean sheets are always nice too!”
Willis, who was Boston’s Player of the Year last season, is a product of the Sheffield United academy, where he still works as an academy coach.
He has previously played for Bradford Park Avenue, Matlock Town, Alfreton Town and Stalybridge Celtic.
Manager Liam King said: "To get a goalkeeper in, the quality of George Willis is brilliant news for this football club.
“He is a player we have been interested in, and certainly one we have admired for a good while & now we just want to get him up and running here at Gainsborough Trinity.
“It is important to thank Craig Elliot at Boston, for his assistance in getting this deal done.”
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