Running for Oromia Police, she was sixth at the Jan Meda Cross Country in February 2008 – a finish which gained her selection for the 2009 IAAF World Cross Country Championships. She finished twelfth at the world event held in Amman and she was part of the silver medal-winning Ethiopian women's team. She travelled to the United States in May and won the Bolder Boulder 10K and was second at the Freihofer's Run for Women. That August she won the 7-mile Falmouth race and set a personal best at the New York City Half Marathon, coming in second place behind Paula Radcliffe in a time of 1:11:04 hours. Mamitu made her debut over the marathon distance in September and performed well, recording a time of 2:26:38 hours to take third place at the high-profile Berlin Marathon. More improvements came at the Delhi Half Marathon, where she finished the race in 68:07 minutes for fourth place. She ended the year with a win at the Obudu Ranch International Mountain Race in Nigeria.