Henri Lansbury was with Norwich until the age of 9 when he followed Roy Massey to Arsenal. By the tme he was 14, he was training with Arsenal's Under-18s and is seen as one of their brightest prospects. A central midfielder, Henri played for England in the UEFA Under-17 competition held in May but was injured in the semi-final win over France and so missed the final which England won

Lansbury made his first team debut for Arsenal in the autumn of 2008 in the 3-0 Carling Cup victory over Sheffield United.

On Transfer Deadline Day (2nd February 2009), Henri was loaned out to Scunthorpe. He helped them to win promotion to the Championshp and reach the final of the Johnstone Paint Trophy

Lansbury then competed for England in the European Under-19 championship; and reached the final before losing 2-0 to hosts Ukraine. Scunthorpe manager Nigel Adkins then expressed his interest in having Lansbury return to Scunthorpe.

On 1st September 2009, Henri was loaned to Malky Mackay's Watford until 31st December 2009. This was extended until the end of the season. Henri made 37 appearances for Watford, scoring five goals.

On his return to Arsenal, he made his Premier League debut in the 4-0 thumping of Fulham on 9th May 2010.

During 2010/11 his Arsenal appearances have been restricted to the Carling Cup, although his last outing brought him a goal in the 4-1 North London derby win over Tottenham at White Hart Lane in September.

His made his full debut for England Under-21s in Germany in November 2010 – and played the final 32 minutes of a 2-0 defeat as an emergency goalkeeper after substitute Jason Steele, who had replaced Scott Loach, had been sent off

On 22nd November 2010, he joined Norwich on a month's loan as cover for the injured Korey Smith, Matthew Gill and Stephen Hughes

Lansbury made his debut for City on 28th November 2010 in the Old Farm derby clash with Ipswich which the Canaries won 4-1. Lansbury had an impressive game and was involved in the second of Grant Holt's three goals. Lansbury's spell at Carrow Road was then extended until 16th January 2011

Lansbury returned to Arsenal in mid-January having made 5 appearances for Norwich. A hamstring injury sustained against Coventry denied him further appearances. He returned to Norwich on 21st January 2011, signing on loan until the end of the season

On 20th March 2011 Lansbury came runner-up to Ipswich's Connor Wickham in the Young Player of the Year at the Football League Awards

Norwich won promotion to the Premiership, on 2nd May 2011 with a 1-0 win at Portsmouth with Henri playing a key role (23 appearances, 4 goals) in the Canaries' promotion challenge.

Linked in July 2011 with a switch to Bolton as a makeweight in Arsenal's bid for defender Gary Cahill, Norwich reportedly made a £1.5million bid for him. Despite being linked with QPR, Norwich and Blackburn in the August 2011 transfer window, Henri was loaned to West Ham on 31st August 2011 days after appearing as a substitute for the Gunners in their 8-2 defeat at Manchester United. Henri will stay with the Hammers until the end of the 2011/12 season. He made 22 appearances for the Hammers

On 28th August 2012, lansbury signed for Notts Forest for £1million, signing a four year contract and becoming manager Sean O'Driscoll's ninth signing of the summer. He had played just eight games for Arsenal.

Lansbury was reported to be a £5million target for Premier League newboys Burnley in August 2014. A year later, Burnely, newly relegated to the Championship, made a £4million bid for Lansbury's services.

The rumour mill in January 2017 saw Villa linked with a £3million move tor Lansbury with Derby, Watford and West Brom also allegedly interested. Norwich were then linked with a swoop for their former player but he instead joined Villa on 20th January 2017 for £2.75million. He had played 150 games for Forest, scoring 33 goals and was their captain at the time of his transfer.

Lansbury was a bit player, making just five appearances, in 2018/19 as Villa won promotion to the Premier League via the play-offs.

His contract was cancelled by Villa at the end of January 2021 and he signed for Bristol City on 29th January 2021. He had played 53 games and scored two goals for Villa. Lansbury's contract was not extended at the end of the 2020/21 season and it was announced on 14th May 2021 that he was leaving the Robins. He had made 16 appearances, four as substitute and received one red card.

On 18th June 2021 he signed for Luton Town along with Cameron Jerome. Luton boss Nathan Jones added that Lansbury came "very well recommended" by former team-mate Chris Cohen, first team coach at Luton, and provides "real know-how at the level, but also that real top-end quality. He's a fantastic midfield player, has had a wonderful career, been promoted from the division more than once, has played for some massive clubs and has real good pedigree,"

Lansbury left Luton on 1st June 2023 having played 48 games for the Hatters but was not involved in their Championship play-off final win over Coventry.

On 28th July 2023 he announced his retirement, following a debilitating injury in late 2022 which left him requiring serious surgery. He set up a new business developing organic fertiliser which has been used by Fulham and sides in Europe.