Souleiman's first international appearances came in 2009, when he placed tenth in the 1500 m at the
Jeux de la Francophonie and ran in the heats of the 3000 m at the
World Youth Championships. In 2011, Souleiman won the title of 1500 m of the
2011 Pan Arab Games in
Doha, in a time of 3:34.32, to win his country's first medal in this competition. He also placed sixth in the 1500 m at the
2011 All-Africa Games. The following season saw him appear on the global scene, as he reached fifth in the final at the
2012 IAAF World Indoor Championships. Souleiman set the Djiboutian national indoor record in the 3000 m at the
Indoor Flanders Meeting in February 2013, coming third with a time of 7:39.81 minutes. In June 2013 he ran a national record at 800 m at a meet in Sweden. Souleiman won the bronze medal at the
2013 World Championships in Athletics held in
Moscow in August 2013, finishing behind
Mohammed Aman of Ethiopia and
Nick Symmonds of the United States. In 2014, Souleiman also won the Bowerman Mile at the Prefontaine Classic, held at Hayward Field in Oregon with a time of 3:47:32. ==Personal bests==