Mahamadou Diarra (born 18 May 1981 in Bamako) is a Malian footballer who plays as a defensive midfielder for Fulham and the Mali national team, for whom he is captain.

Diarra started his career with Greek side OFI Crete. He played for French club Lyon from 2002 until 2006 and formed a successful midfield partnership with Michael Essien. He won four Ligue 1 titles during his time at Lyon, playing a key role in the teams success.

After Real Madrid coach Fabio Capello asked President Ramón Calderón to sign three players, "Diarra, Diarra and Diarra", Real Madrid joined Manchester United in the race to sign Mahamadou Diarra. Lyon said that Diarra could not leave and put a €40 million price tag on him, which matched the price Chelsea paid Lyon for Michael Essien in the summer of 2005. On 18 August 2006, Real Madrid agreed a fee of €26 million. On 22 August, Diarra was unveiled at the Santiago Bernabéu by Calderón and was assigned the number 6 shirt.

In 2006–07, Diarra was a staple player in Fabio Capello's two-defensive midfielder system. He played in 33 of Madrid's 38 matches, scoring three times. He lost his first team spot at one point after he and Antonio Cassano were caught on camera making fun of Capello during a training session. On 18 June 2007, with Real Madrid needing to win against Real Mallorca to win the league title for the first time since 2003, Diarra scored an 81st minute header to give Madrid a 2–1 lead. In the 84th minute, José Antonio Reyes scored a third goal to ensure Real Madrid were champions.