Scottish international defender Grant Hanley joined Norwich on 30th August 2017 from Newcastle for an undisclosed fee, signing a four year deal. Norwich's management were forced to act after conceding 4 goals in their two previous games (a 4-2 defeat at Aston Villa and a 4-0 defeat at Millwall). Manager Daniel Farke said "It is clear our defensive line needs strengthening, Grant is a quality defender with very solid experience and is a leader too. I really like his attitude and his desire to come and play for us as well as the attributes he will add on the pitch."

Hanley was involved at youth level with local club Queen of the South before joining Crewe's academy in 2004. He moved to Rangers in 2006 but returned to England in 2008 to join Blackburn Rovers where he captained the Under-18 side. Hanley made his Premier League debut for Rovers in a 1–0 win at Aston Villa on 9 May 2010. He made nine top flight appearances the following season and won his first Scottish cap on 25th May 2011 against Wales in the Nations Cup in Dublin (he had been capped by Scotland at Under-19 and Under-21 level).

In the 2011/12 season, he made 28 appearances but Rovers were relegated into the Championship. He was later appointed club captain and made a total of 200 appearances for Rovers.

On 21st July 2016, he signed for Newcastle who had been relegated to the Championship. He made 16 appearances, scoring once against QPR, as Newcastle won the title.

Hanley made his Norwich debut as a late substitute in the 1-0 win over Birmingham on 9th September 2017. Similar substitute appearances followed against Sheffield United and Middlesbrough (both won 1-0 away from home). Hanley scored his first Norwich goal in the 3-2 win over Reading on 17th March 2018. He ended the season with 34 appearances but no further goals.

Hanley made 10 appearances, scoring once, the following season in which Norwich won promotion to the Premier League by securing the Championship title.

On 24th June 2019, it was reported that Blackburn manager Tony Mowbray was keen on bringing Hanley back to Ewood Park.

Despite missing much of the 2019/20 season through injury, contributing to Norwich's relegation, media reports linked him with a move to Burnley in late July 2020. He had made just 18 appearances in 2019/20, scoring once.

On 29th April 2021 he was named in the EFL Championship Team of the Season and came second in the Barry Butler Trophy for Norwich's Player of the Season. He made 44 appearances for Norwich in 2020/21, scoring once, as Norwich won the Championship title.

Hanley played the full 90 minutes for Scotland in their opening game in the European Championships on 14th June 2021; their first appearance at the finals of a major tournament since 1998. Unfortunately they lost 2-1 to the Czech Republic. He then had a strong game as Scotland held England to a 0-0 draw at Wembley but in the third game against Croatia, he was forced off midway through the first half with a hamstring injury and will be out of action for four weeks.

He made 36 appearances, scoring once, in 2021/22 as Norwich finished bottom of the Premier League.

He made 41 appearances for Norwich during the 2022/23 season.