Diallo started his career in France playing for AS Brevannes and Sedan before moving to Belgium and playing for RC Tilleur and KV Mechelen.
In 2003 Mechelen went into liquidation and Diallo was released on a free transfer. He promptly moved to England and signed for Burnley. Although the Lancashire club were keen to sign Diallo on a long term deal after he had impressed Stan Ternent during his time at the club, Diallo spent just 5 months in Burnley before Joe Royle swooped to sign him for Ipswich Town at the end of the season. He scored two goals for Burnley, against Fulham in the FA Cup and Gillingham in the league.
Drissa completed a two-year contract at Portman Road and helped Ipswich reach the Championship play-offs, but his time there was marred by injury trouble and he was released by the club in the Summer of 2005.
Sheffield Wednesday manager Paul Sturrock then brought Diallo to the newly promoted Championship club one month later. Diallo turned out some satisfactory displays at Hillsborough, but his season was again peppered with injuries and on 4 May 2006 it was announced that Wednesday would not be renewing his contract upon expiry at the end of the season.
Diallo was signed on a free transfer in July 2006 along with Jon-Paul McGovern by Milton Keynes Dons.
On September 18, 2008 Diallo joined Cheltenham Town on a one month loan and then on the 2nd of January 2009 Drissa was officially named a Cheltenham player following a free transfer after the successful loan spell.