Early career Freweyni Hailu gained her first international experience in 2018 at the
World Junior Championships in
Tampere, Finland, where she placed fifth in the women's
800m event. The next year, she was fourth in the under-20 800m race at the
African U18–U20 Championships in
Abidjan, Ivory Coast. Freweyni competed in the women's
800 metres at the
2019 African Games, where she was eliminated in the semi-finals. She,
Lemlem Hailu, and
Diribe Welteji were named to the Ethiopian team. At the Games, she finished in fourth place in a time of
3:57.60 behind only, 1–3,
Faith Kipyegon,
Laura Muir and
Sifan Hassan. On 14 September 2021, at the
Hanžeković Memorial in
Zagreb, Freweyni set an Ethiopian record for the
2000 metres with a time of 5m 25.86s, finishing behind only
Francine Niyonsaba who set in this race a world record of 5:21.56. Freweyni's mark was the third-fastest in history. Hailu placed fourth over 1500 metres at the
2022 World Athletics Championships in Eugene, Oregon in July 2022, running 4:01.28 behind Kipyegon, Muir, and compatriot
Gudaf Tsegay. She finished seventh in the 5000m at the
2023 World Athletics Championships in
Budapest in 14:58.31. In October, she was runner-up in the mile run at the
2023 World Athletics Road Running Championships in
Riga, Latvia, finishing behind her world record setting compatriot Diribe Welteji, running 4:23.06 for second place ahead of Faith Kipyegon. At the
2024 Copernicus Cup in February 2024, she set a new 1500m personal best, running 3:55.28. She won the gold medal in the final of the
women's 1500 metres race at the
2024 World Athletics Indoor Championships in
Glasgow. In May 2024, she led from the front to win the 1500 metres at the
2024 Doha Diamond League. Later that summer, she placed second behind Kipyegon in the 1500 metres at the
2024 Golden Gala in Rome, and third over 5000 metres at the
2024 Prefontaine Classic. The following week, she won over 3000 metres in 8:19.98, improving on the world-leading mark she had set in Ostrava nine days prior and moving up to third on the world indoor all-time list, in
Liévin on 13 February 2025. She was awarded a wild card place for the
2025 World Athletics Indoor Championships in
Nanjing, China, for her performances on the
2025 World Athletics Indoor Tour. At the championships, she won a gold medal in the women's 3000 metres race for her second World Indoor title. Competing in the
2025 Grand Slam Track event in Miami in May 2025, she won the 1500 metres and finished third in the 800 metres to win the overall two-race format in the women's short distance category. On 6 June 2025, she ran a personal best 14:19.33 to finish second over 5000 metres at the
2025 Golden Gala in Rome. In September 2025, she was a finalist over 1500 metres at the
2025 World Championships in
Tokyo, Japan, placing sixth overall.
2026 In February 2026, Hailu went into an early world lead with a time of 8:24.59 for the 3000 metres in Liévin, France, finishing ahead of her compatriot and world U20 champion
Aleshign Baweke and Italian
Nadia Battocletti.{{cite web|url= https://www.european-athletics.com/home/news/0-03-off-the-european-record-battocletti-clocks-8-26-44-for-3000m-in-lievin|website=European Athletics|accessdate=19 Feb 2026|title= 0.03 off the European record! Battocletti clocks 8:26.44 for 3000m in Lievin|first=Steven |last=Mills ==Competition record==