West Ham United Diangana joined the
West Ham youth system in 2010, aged 12. Originally a
striker, he began playing as an attacking midfielder at under-15 level. He made his under-18 debut for the club in February 2014, and his
Premier League 2 debut in January 2015. He signed his first professional contract with the Hammers on 14 May 2016. On 26 September 2018, Diangana made his first team debut in the
EFL Cup against
Macclesfield Town, playing the full game and scoring two goals in an 8–0 victory at the
London Stadium, in which fellow debutants
Conor Coventry and
Joe Powell also featured. Three days later, Diangana made his first
Premier League appearance, coming on as a 93rd-minute substitute for
Felipe Anderson in a 3–1 home victory against
Manchester United. Diangana became a regular in the team following an injury to
Andriy Yarmolenko, making his first Premier League start against
Leicester City on 27 October and registering his first league assist in the following game, against
Burnley. On 18 January 2019, Diangana signed a new six-year contract that would have kept him at West Ham until 2025.
Loan to West Bromwich Albion On 8 August 2019, Diangana joined
West Bromwich Albion on loan until the end of the season He made his West Brom debut on 13 August 2019 in a 2–1 home defeat by
Millwall in the first round of the
EFL Cup. Diangana scored his first two goals for West Brom on his league debut, on 17 August 2019. Coming on at half-time for
Kyle Edwards against
Luton Town, scoring two goals in six minutes in a 2–1 win which ended Luton's run of 28 home games unbeaten. Diangana played 30 times in the league for Albion, scoring eight goals as they won promotion to the Premier League. This included a goal and an assist in the final game of the season, a 2–2 draw against
Queens Park Rangers as Albion returned to the top flight after a two-year absence.
West Bromwich Albion On 4 September 2020,
West Bromwich Albion announced the signing of Diangana for an undisclosed fee on a five-year deal. The decision to sell him by West Ham chairman
David Sullivan was controversial at the time amongst both fans and players. West Ham club captain
Mark Noble openly stated that he was "angry and sad that Grady has left" in a comment which gathered support from fellow players including
Declan Rice and
Jack Wilshere. Diangana scored his first Premier League goal in a 5–2 defeat to
Everton. It was a long-range solo effort from 20 yards out which beat
Jordan Pickford into the bottom right hand corner. Despite a difficult start to the season for West Brom, Diangana was a regular starter on the
left flank under manager
Slaven Bilić. After 202 appearances and 26 goals, Diangana was released by West Brom at the end of the
2024-25 season upon the conclusion of his contract.
Elche On 30 August 2025,
Elche CF of the
Spanish First Division announced the signing of Diangana on a two-year deal. ==International career==