The 24-year-old is to become Paul Lambert's fifth new addition of the summer, following strikers James Vaughan and Steve Morison, winger Elliott Bennett from Brighton and young Belgian defender Richie De Laet on loan from Manchester United to Carrow Road as the Norfolk club prepare for a first Barclays Premier League campaign since 2005.
Johnson, 24, told the club's official website, www.canaries.co.uk: "I am over the moon really to get the chance to play in the Premier League with a big club like Norwich City and under a great manager who I have a lot of respect for."
He added: "He is done a fantastic job since he arrived at Norwich and that was one of the main factors in me signing with the club."
Norwich are also said to be closing in on Anthony Pilkington after Huddersfield revealed the 23-year-old winger had asked to leave.
Source: PA
Source: PA