Diallo came to the United States in 2007 to play for Rochester Raging Rhinos in the USL First Division. During the 2007 season with Rochester, Diallo was a regular starter up front along with English-born strikerMatthew Delicate; however, during 2008 Diallo gradually became a less frequent member of new coach Darren Tilley's squad, and had only eventually logged 474 minutes of playing time in 13 USL matches during the 2008 season.
On July 9, 2008, Diallo was transferred to Carolina RailHawks in return for Jamil Walker. Diallo produced a top-notch season with RailHawks in his debut season, where he recorded a hat-trick against the Seattle Sounders despite losing the match on a score of 4-3. He finished off the season by scoring seven goals and registering three assists in 16 games to finish with a team-leading 17 points. Despite a promising debut season, Diallo unfortunately failed to regain his previous form that dominated the 2008 season; which led to limited playing time during the 2009 season. On March 8, 2010 the Real Maryland Monarchs announced the signing of Diallo to a contract for the 2010 season. Since being released from Maryland in 2010 Diallo has been working part-time in a fast food restaurant in the Roquette area of Paris.