Grant Holt became Norwich's biggest signing of the 2009 pre-season when they paid a fee rumoured to be £400,000 for his services to Shrewsbury.

In his early career, Grant played for a number of non-league sides including Barrow, Workington, Halifax Town and in Singapore with Sengkang Marine, before he was signed by Sheffield Wednesday in 2003/4, for whom he would make 30 appearances, scoring 4 goals.

Released to Rochdale in January 2004, Grant scored 42 goals in 83 appearances and earned a £300,000 switch to Notts Forest in January 2006. He had a slow start to his Forest career and nearly joined Bristol City in November 2006. He persevered at Forest and eventually scored 21 goals in 96 games. During this period, he was loaned to Blackpool

On 24 June 2008, Shrewsbury Town broke their club transfer record by signing Holt for £175,000. During the 2008/9 season, he scored 28 goals in all competitions for the Shrews including five in their 7-0 Football League Trophy win over Wycombe on 7th October 2008.

Holt made his debut for Norwich in the 7-1 shock home defeat to Colchester on the opening day of the 2009/10 season but scored a hat-trick in his second appearance; the 4-0 Carling Cup victory at Yeovil on 11th August 2009.

In his first season at Carrow Road, Holt scored 30 goals and was named Player of the Season.

In December 2010, after an impressive start to life in the Championship and a hat-trick against Ipswich, Grant was linked with a move to the Premiership with West Ham, Wigan, Blackpool and Bolton all linked with him. Norwich responded with a six word statement "Grant Holt is not for sale"

On 20th March 2011 Holt came runner-up to QPR's Adel Tarabaat in the Championship Player of the Year at the Football League Awards. He was named in the 2011 PFA Championship Team of the Year.

Norwich won a second promotion, moving up to the Premiership, on 2nd May 2011 with a 1-0 win at Portsmouth with Holt's goals playing a key role in the Canaries' promotion challenge. He played 48 games, scoring 23 goals. He was also voted Player of the Season again.

Holt was the subject of a bid from Rangers in January 2012

At the end of February 2012, Grant was voted into Norwich City's Hall of Fame

Holt was named Norwich's Player of the Season for the third season in May 2012, having scored 17 goals in 38 appearances. On 18th May 2012, he submitted a transfer request that was rejected by the Canaries. This came two days after he was omitted from England's Euro 2012 squad despite being the second highest English scorer in the Premiership. This was re-iterated and re-expressed at the end of June 2012, with his agent reporting that Norwich were unwilling to give grant a "third year" on his new two year contract as he was "too old". The Daily Mail speculated that Holt would follow Paul Lambert to Aston Villa although David McNally expressed that Holt was not for sale. West Ham were reported to have made a £3m bid for Holt, this was allegedly increased to £5.5m on 20th June 2012

After discussions with new manager Chris Hughton, Holt signed a three year contract on 3rd July 2012. Holt said: “I’m really pleased we’ve agreed things and that I’ve got a three-year deal which gives me and my family a bit of security. I do appreciate where the club was coming from in terms of the process we’ve gone through to get to this point. Now I’m just really keen to concentrate on getting back to work with the rest of the lads and concentrating on having a good pre-season and getting ready for the start of another season in the Premier League.”

Norwich City boss Chris Hughton said: “I said when I first arrived that talking to Grant was a priority as what he has achieved for Norwich and what he brings to the squad is there for all to see. It’s great news that he has signed a new contract and I’m really looking forward to getting down to work with Grant and the rest of the players when we return to training next week.”

At the end of May 2013, Grant was the subject of an enquiry from Australian side Melbourne Heart. He was then linked with moves to Crystal Palace, Wigan and Hull. On 8th July 2013, he completed a move to Wigan for an undisclosed fee, reported to be £2million. Holt signed a three year deal with the Latics and became owen Coyle's eight signing of the 2013 pre-season.. It was widely accepted that Holt wanted to move up north to be closer to his family in Carlisle.

Holt scored on his Wigan debut, a 4-0 thrashing of Barnsley on 3rd August 2013. However he struggled to score further goals, netting just once more in 21 appearances. On 14th January 2014, he was surprisingly re-united with Paul Lambert who signed him on loan for Aston Villa until the end of the 2013/14 season. "When I knew Grant had become available it was something I wanted to pursue quickly because he'll add strength and experience. Having worked with him for three years at Norwich, I know what he can do," said Lambert. Holt said "It's a massive opportunity for me personally, an opportunity I couldn't turn down. To be able to come back into the Premier League, especially at a club as big as Villa, is fantastic." Holt made his Villa debut in the 2-2 draw at Liverpool on 18th January 2014 as did fellow loan signing Ryan Bertrand. Holt made 10 appearances for Villa, scoring once.

Out of favour at Wigan and training with the Under-21 development squad, Holt was loaned to Huddersfield on 26th September 2014, making his debut the same day in a 2-1 win over Millwall.

Holt and Wigan were releaged to League One on 28th April 2015 when Rotherham beat Reading 2-1 consigning Wigan and Millwall to the two remaining relegation spots along with Blackpool

After missing the second half of the 2014/15 season through injury, he was loaned to Wolves on 30th October 2015 until 2nd January 2016.

Holt was released by Wigan at the end of January 2015 and he was linked with moves to Carlisle, Oldham and Hearts.

On 18th February 2016, Holt rejoined Rochdale on a deal until the end of the season. They announced at the beginning of May 2015 that they would not be renewing his contract.

On 29th June 2016, he became Neil Lenoon's first signing as Hibernian manager, signing a one year contract. Holt told Hibs TV: "I said to the gaffer I'm not here just to sit and help the young lads along. I've come to play football. I've been out a long time with my knee, I've come back and I'm fit. I want to score goals and enjoy my football." Holt had been a regular in the side but didn't play when Hibs beat Queen of the South 3-0 on 15th April 2017 to secure promotion to the Scottish Premiership. Holt though was released, along with five other players, on 12th May. He had scored seven goals in 39 appearances.

On 9th October 2017, Holt and fellow former Canary Simon Lappin signed for Ian Culverhouse's Kings Lynn Town. Holt made his debut as substitute in the 2-0 win over Hitchin on 10th October.

After four appearances and one goal for Lynn, Holt left the Linnets on 9th November to re-join Barrow, managed by Ade Pennock, as player-coach. Holt left Barrow on 20th July 2018 having made 23 appearances for them.

He rejoined Norwich as a coach in the Academy in August 2018 combining it with the Director of Football role at the Langley School. Holt will work with the under-23 squad and the lower age groups for one day a week, when schoolboy players are also in on school day release, and continue his work as a commercial ambassador for City. He then announced his retirement from playing on 24th August 2018.

This was renounced on 6th October 2018 when he signed for Thurlow Nunn Eastern Counties side Wroxham managed by former colleague Adam Drury and featuring former Lynn teammate Simon Lappin. Holt made his Wroxham debut on 7th October 2018 in the second round of the Norfolk Senior Cup against Fakenham Town and scored the first goal in a 2-0 win.

After scouting for Norwich for two years, he joined West Ham's first team scouting department at the beginning of December 2021. Speaking about his new role, the City legend told Jimmy Bullard on his SkyBet show: '"'ve just got a new job as a first-team scout at West Ham. A friend of mine gave me a phone call and said there were a few jobs going there. I've been doing it at Norwich for nearly two years now and I thought that it looked like a really good opportunity. I put my name in the hat and they've said 'come along and have a chat' and I'm looking forward to it. It's a great club on the rise, getting into Europe and that. I'm very lucky. It's a great opportunity for me." His role is about making recommendations that will both improve Moyes' team and represent value for money. 

On 28th January 2024, Dereham Town announced the formation of a new strategic relationship with a group of local people, including ex-Norwich City striker Grant Holt. The consortium will be advising and supporting the club’s existing committee on day-to-day football operations, as well as taking the lead on all business related aspects at Aldiss Park - building long-term strategy and sustainability. The consortium’s aim will be to protect the long-term security of the club from a financial perspective and deliver a new strategic focus to allow it to grow and succeed on and off the pitch.

Holt said “I began my career playing in non-league, and I know the importance of preserving these clubs and the value of the role that they play in the community. I’m a passionate advocate for local football in Norfolk, and there are few sides with the potential that Dereham Town FC possesses. I look forward to bringing my expertise into the club - both from my playing career and work within the game after my retirement. The consortium is a really exciting mix of extremely talented and experienced people from the Norfolk business community who will work to develop the future of Dereham Town FC and make it a more sustainable and, hopefully, successful club in the future. I look forward to meeting supporters at Aldiss Park in the future and am really excited about this new opportunity.”

Holt made his Dereham debut in the Norfolk Senior Cup clash with Norwich City's Under-21s on 30th January 2024 but didn't score in a 2-1 defeat to the young Canaries.