Diarra is described as a player who is "strong, athletic and very powerful" and possesses a "combative edge" similar to former French international Patrick Vieira.

[6] Diarra and his siblings were raised in the neighborhood of Rose des Vents located in the nearby commune of Aulnay-sous-Bois, where his parents still reside.

On 28 May 2010, ahead of the 2010 FIFA World Cup, Diarra departed the national team's training camp to be beside his wife as she gave birth to his second child.

Diarra was a regular within the team playing alongside the likes of Owen Hargreaves, Philipp Lahm, Bastian Schweinsteiger and Zvjezdan Misimović.

Hoeneß admitted that he was surprised by Diarra's resurgence, stating: "If somebody had told me [he would return for a UEFA Champions League game] five years ago and made a bet with me, I would have lost a fortune".

[13] Since Diarra departing the club in 2002, due to FIFA compensation laws, Bayern have recouped over €800,000 as a result of the player's future transfers.

[18] On 3 July 2002, English club Liverpool confirmed its interest in signing Diarra under the guidance of manager Gérard Houllier, who had likened the player to Patrick Vieira.

[12] Louhans-Cuiseaux reported the situation to FIFA, however, the organization ruled in favor of Diarra who was allowed to continue his career with Le Havre.

In the 2003 off-season, Diarra admitted that he would love to return to Liverpool stating "I'm someone who is ambitious and I hope to win my place at Anfield next season".

[29] Upon his arrival to the club, Diarra was inserted as a starter by manager Gérard Gili and paid immediate dividends scoring in back-to-back weeks in a 4–2 win against Guingamp and a 4–1 loss to Auxerre in September.

After the season, Diarra returned to Liverpool for pre-season training, however, not under the guidance of his recruiter Houllier, but under Spanish coach Rafael Benítez.

[38] After finishing the season, on 24 June 2005, Liverpool granted his request after Lens reached an agreement with the club on a transfer fee, purported to be €3.2 million.

Diarra remained a starter at Lens and also retained his consistency appearing in a career-high 44 matches, scoring two goals, and providing four assists.

He made his European debut on 3 July 2005 in a UEFA Intertoto Cup second round tie against Polish club Lech Poznań.

Following the 2006 FIFA World Cup, Diarra was linked with a move to the then five-time defending champions Lyon where he could reunite with former manager Gérard Houllier.

[47][48][49] The feud culminated on 6 April when Houllier dropped Diarra from the squad to face Valenciennes the following day and then ordered him to play for the club's reserve team in the Championnat de France amateur, the fourth level of French football.

[51] The defensive midfielder did not budge and, subsequently, missed the team's next four league matches, as well as the 2007 Coupe de la Ligue Final.

[65] In the 2008–09 edition of the UEFA Champions League, Diarra appeared in all six group stage matches Bordeaux played in and scored a goal against English club Chelsea in a 1–1 draw.

Bordeaux, subsequently, went on a six-match winning streak to close out the season, which resulted in the club capturing the sixth title in its history and its first since 1999.

He began the season claiming his fourth silverware with Bordeaux on 25 July 2009, winning the 2009 Trophée des Champions title in a 2–0 victory over Guingamp.

[74] A week later, Bordeaux president Triaud stated that Marseille had failed to meet the player's €7.75 million release clause and that Diarra was likely not going to be leaving the club.

[87] On 10 August 2012, Diarra moved back to England to join West Ham United on a three-year contract, for an undisclosed fee.

[90] Diarra made his debut for West Ham on 25 August in a 3–0 away defeat to Swansea City coming on as a 69th-minute substitute for Mohamed Diamé.

[102] On 23 February 2015, Diarra signed a deal with Championship side Charlton Athletic to last until the end of the season and scored his first goal in a 2–1 loss to rivals Millwall.

[107] On 15 October 2016, Diarra scored Nancy's only goal in a 2–1 home defeat against Paris Saint-Germain in a Ligue 1 match by heading in Benoît Pedretti's free kick from the right in the 55th minute.

On 13 August 2004, Diarra was named to the senior national team for the first time by Domenech to participate in a friendly match against Bosnia and Herzegovina.

After appearing in a November 2006 friendly match against Greece, Diarra was absent from the national team for nearly two years, partly due to his struggle for playing time in Lyon.

After regaining his form at Bordeaux, Diarra began making his way back into the team and participated in seven 2010 FIFA World Cup qualifying matches.

France endured a disastrous campaign as the players went on strike in response to its disagreement over the expulsion of striker Nicolas Anelka from the team.

After missing the August 2010 friendly due to suspension, he returned to the team in September playing the entire match in 2–0 wins over both Bosnia and Herzegovina and Romania.