Lemlem Hailu gained her first international experience in 2017 at the U18 World Championships in Nairobi , where she won the gold medal in 4: 20.80 minutes. The following year, she also won the African Youth Games in Algiers in 4: 36.71 minutes and thus qualified for the Youth Olympic Games in Buenos Aires , where she won the bronze medal. In 2019 she took part in the Africa Games in Rabat for the first time and won the bronze medal there in 4: 20.60 minutes behind the Kenyans Quailyne Jebiwott Kiprop and Mary Kuria . In February 2020 in Toruń , Hailu improved the U20 indoor world record held by her compatriot Gudaf Tsegay over 1500 meters to 4: 01.79 min.
In 2019 , Hailu became the Ethiopian champion in the 1,500 meter run.