Born in Dakar, Dabo began his career with ASC Yeggo and he then joined French club Saint-Étienne's youth academy when he was 14 years old. In the summer of 2004 he was promoted to the club's senior team by manager Élie Baup. On 7 May 2005, Dabo made his debut for Saint-Étienne in a 2–0 win over Toulouse and made three appearances in total in his first season. Baup's successor Ivan Hašek put Dabo in the right-back position before newly manager Laurent Roussey switched him into the left-back role. Dabo's second season proved to be the breakout year for the player as he received more playing time. On 21 September 2008, Dabo scored his first goal for Saint-Étienne against Paris Saint-Germain. The result was 1–0 in favor of Saint-Étienne. On 7 February 2009, Dabo scored an own goal against Caen. However, Saint-Étienne won the match 3–2 with goals from Bafétimbi Gomis and Ilan, who scored twice. In January 2009, club manager Alain Perrin told Le Progrès that Dabo, who had one year left on his contract at the time, refused all proposals on an extension.
Sevilla
Following his contract expiration, Dabo signed a four-year contract with Spanish club Sevilla on a free transfer, making him the first signing for the club. He made his debut for Sevilla in the first leg of the team's Supercopa de España tie against Barcelona on 14 August 2010. Two weeks later, Dabo made his league debut for Sevilla in a 4–1 win over Levante. On 19 December 2010, he received his first red card of his career after he kicked goal-scorer Ángel Di María in a 1–0 loss against Real Madrid.
Lyon
After just one season in Spain, in August 2011, Dabo returned to France signing a four-year contract with Lyon. The transfer fee was priced at €1 million plus a possible €800k in incentives. On 18 September 2011, Dabo made his debut for Lyon in a 2–0 win over Marseille after coming on a substitute for Anthony Réveillère. On 29 October 2011, he played his first match against his former club Saint-Étienne in a 2–0 win, but received a straight red card in the second half after foul on Bănel Nicoliță. In the Coupe de la Ligue, Dabo received his second red card of the season 2–1 win over Lille on 11 January 2012.
Following his release by Lyon, Dabo completed a move to newly promoted Ligue 1 club Troyes on 14 October 2015. He made his Troyes debut on 25 October in an away match against Bordeaux in Ligue 1.
