[4] He began his football career with junior team Ndeffann Saltigue before joining ASC Diaraf of the Senegal Premier League in 1996.

[4][6] In December that same year, he joined fellow top-flight club Grasshoppers,[7] whom he helped win the championship title in his first half-season[8] and made his first appearance in UEFA competitions the next.

[11] An injury due to hamstring, foot, and back problems resulted in him missing part of the 2006–07 season and losing the captaincy to Danny Murphy.

In January 2007 Wigan Athletic made a £5 million bid for the midfielder, but Diop decided against the move and stayed with Fulham, helping them to avoid relegation.

[22] Diop was a key player in Portsmouth's victorious 2008 FA Cup campaign, playing a solid, defensive game and making some crucial tackles against Cardiff City.

[21] On 13 July 2010, Diop agreed terms with AEK Athens signing a two-year deal earning €900,000 per season,[25] despite interest from Fulham, Celtic and Paris Saint-Germain.

[26] Diop made his debut for AEK Athens against Dundee United on 19 August 2010 in a Europa League play-off first-leg game.

[40] With Hayden Mullins suspended and Jonathan Spector injured for the visit of Crystal Palace on 15 December,[41] Diop made his first start for Birmingham, alongside League debutant Callum Reilly in central midfield.

He scored the equalising goal, a powerful header from Rob Hall's corner, as Birmingham came back from 2–0 down to draw,[42] and was rewarded with another month's contract.

[44] Bouba Diop received his first call-up to the Senegal national squad in 1999, at the age of 21, while playing for Neuchâtel Xamax in the Swiss Super League.

He was part of their squad that finished runners-up at the 2002 Africa Cup of Nations in Mali, and scored the opening goal of a 2–1 win over Nigeria in the semi-finals.

[46][47][48] Diop played at three more Africa Cup of Nations tournaments: in 2004 he scored in a 3–0 group win over Kenya in Tunisia,[49] and in 2006 he netted in a 3–2 victory against Guinea in the quarter-finals.

[50] His last appearances were in a group-stage elimination in Ghana in 2008, in which Senegal manager Henryk Kasperczak resigned during the tournament due to the team's ill discipline.

[53] His manager at Fulham, Chris Coleman, described him as a player with "great feet, scores goals, defends well, tackles, has got good pace", and that his "stature and ability" were unique in the Premier League at the time, similar to that of Patrick Vieira.

[54] Former Manchester United midfielder Paul Scholes described him as one of the most "awkward" players he had played against, and noted that "you get involved physically with him and you're wasting your time".