Mesfin won his first major medal at the 2007 African Junior Championships in Athletics, taking the 10,000 metres silver medal behind Kenya's Mathew Kisorio. His first year of global competition came in 2008. He was eleventh in the junior race at the 2008 IAAF World Cross Country Championships – a performance which helped Ethiopia to the team silver medals. He just missed out on a medal at the 2008 World Junior Championships in Athletics, finishing fourth behind fellow Ethiopian Ibrahim Jeilan. He competed for Ethiopia at the International Chiba Ekiden and won his race stage, helping the national team to the title. He ended the year with a third-place finish at the inaugural Bahir Dar Cross Country.