Tolossa Kotu represented Ethiopia at the 1972 Summer Olympics in Munich in the 5000 metres, but failed to qualify for the final. At the 1980 Olympics in Moscow Kotu ran the 10,000 metres, winning his heat. In the final he stayed with the leaders until the last lap, placing fourth behind Miruts Yifter, Kaarlo Maaninka and Mohammed Kedir. "Track &amp; Field News" ranked him the seventh-best 10,000 m runner of 1980, behind the three runners he lost to at the Olympics and three whose countries boycotted the Olympics (Craig Virgin, Henry Rono and Toshihiko Seko); this was the only time he was ranked in the world's top 10. In 1981 he represented Africa at 5,000 metres in the 1981 IAAF World Cup in Rome, placing fifth.