Demelash had a stellar 2016 season, topping the world rankings, and emerging as a favorite to medal at the Olympics. At the 2016 Summer Olympics in Rio de Janeiro, Demelash competed in the Men's 10,000 metres, finishing in 4th place, only one hundredth of a second behind his teammate, Tamirat Tola. Demelash made a strong surge in the last 10 metres, but Tola was able to reach the finish line quickly enough to elude him.