Lewis, 20, spent most of this season on loan at League Two Morecambe. The last of his 22 appearances for the Shrimps came in a 3-2 victory over Darren Ferguson's side.
A fee of £400,000 plus a sell-on clause is thought to have been agreed and, while the canaries will have been reluctant to let such a hot prospect go, the money could be put to good use in the short term as Glenn Roeder attempts to bolster his squad for the second half of the Championship season.
Lewis has never featured in a competitive fixture for the Norwich first team and, with incumbent David Marshall just 22 years of age, has decided to look elsewhere for regular action. Just a few weeks after joining Morecambe his performances, which earned Sammy McIlroy's side League Cup victories over Wolves and Preston, Lewis was called into Stuart Pearce's England under-21 squad.