The 25-year-old joins the 'Canaries' on a four-year deal for an undisclosed fee.
Hanley only joined Newcastle last summer but made just seven appearances as the 'Magpies' returned to the Premier League at the first time of asking.
The former Blackburn man made his desire for regular football known to Rafa Benitez, who agreed to let him move on after sealing a move for Florian Lejeune.
Upon completing the move, Hanley told Norwich City TV: "Being able to come to a massive club and get games is a big motivation for me.
"It's a club with high aspirations and a fresh start for me. As a defender, I'm a bit of an old-fashioned no-nonsense centre-half and you pride yourself on clean sheets.
"We've got work to do on the training ground to improve that."
Defender Grant Hanley has joined Norwich City from Newcastle United on a four-year deal! #ncfc
— Norwich City FC (@NorwichCityFC) 30 August 2017
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