In May 2015, she confirmed herself as the continent's best 400 m runner in her age group with a gold medal at the 2015 Asian Youth Championships. In June while in Bulgaria, she set national junior records in the 100 m and 200 m clocking 11.70 s and 23.03 s respectively. Eid Naser then proved herself among the best globally in the 400 m at the 2015 World Youth Championships. A patient run in a tight hijab, what was her own decision, saw her overhaul the more favoured American Lynna Irby in the final stages of the race, and she achieved a lifetime best of 51.50 s to take a gold medal. The final came on the day after Ramadan which allowed her to eat normally before the race, after having fasted during the qualifying rounds. The gold medal made her the second ever Bahraini woman to win a global-level title, after senior world champion Maryam Yusuf Jamal. Her tactical running was praised by decathlon world record holder Ashton Eaton, who invited her on an all expenses paid trip to train with him for three days.