Mohajer Shojaei made his debut on the world stage at the age of 19, when he ran a time of 1:50.08 (min:sec) in the 800 metres race at the 2002 Asian Junior Athletics Championships in Thailand.
He won his first gold medal at the 2007 Summer Universiade, running the 800 in 1:46.04, which at the time was his personal best. From this point he gained form for next year's Olympic Games. However, Shojaei did not qualify past the first round in the 800-m race at the 2008 Summer Olympics, running a slightly slower (in comparison to his blistering Universiade victory) 1:49.25.