Amass moves to Carrow Road on-loan to the end of the season after spending the first-half of the campaign with Sheffield Wednesday.
Amass told Norwih's website: "I've spoken to Ben and the coach. They've both said they've watched me at Sheffield Wednesday and a little before that, and they've liked what they've seen.
"They like the way I move the ball, the way I am with the ball, the hard work I show. They spoke to me and said they see that I can do good things here, they think it will be an advantage for the club and for me, so it should be good for both sides."
Sports director Ben Knapper has welcomed Amass' commitment.
“We are delighted to welcome Harry to the football club. Although still at a very early stage in his professional journey, his talent was evident for all to see during the first half of the season during an impressive loan spell at Sheffield Wednesday,” he said.
"He has shown that he is clearly ready to compete and excel at this level, and he will bring quality and strengthen the left-back position for us. He is fit and ready to go, and we look forward to him helping the group and helping to lift the club up the table for the rest of the season."