The 22-year-old is out of contract at Tottenham Hotspur at the end of the month, and the club have confirmed he will not be offered new terms.
The news comes as little surprise after the former England Under-21 failed to make a first team appearance for Glenn Hoddle's side last season. He's previously played 21 times for Spurs.
While a move for Thelwell looks imminent, Peter Taylor has ruled out any chance of bringing Michael Reddy back to Hull.