Against his father's wishes, Yomif dropped out of high school in the ninth grade to pursue running, leading to his expulsion from home.

[7] Yomif made his international debut at the 2013 World Youth Championships in Donetsk, winning gold in the boys' 3000 metres with a time of 7:53.56.

[8][9] In June, he placed second over 3000 m in 7:36.28 at the Ostrava Golden Spike elite meeting, losing only to Kenya's Caleb Ndiku; he defeated 2008 Olympic medallist Nick Willis and former world champion Bernard Lagat.

[8][10] Yomif won the 5000 metres at the World Junior Championships held in July in Eugene, Oregon that year, running 13:25.19.

[8][11] He made his IAAF Diamond League debut in Doha, placing fifth in the 3000 m. He then won a non-Diamond Race 5000 m event at the Prefontaine Classic in Eugene, improving his personal best to 13:10.54 and outkicking Edwin Soi and Galen Rupp.

[12] Yomif scored his first Diamond League victory the following week at the Golden Gala in Rome, winning 5000 m in a world-leading 12:58.39 and breaking 13 minutes for the first time.

[8][13] On 11 September, Yomif competed in the event at the Brussels Diamond League, setting a new personal best and world-leading time of 12:53.98.

Yomif came within hundredth of a second of Hicham El Guerrouj's world indoor mile record on 9 February at the Millrose Games.

[20] At the end of the 2023 outdoor season, on 17 September, Yomif competed in the 3000 metres at the Diamond League Final (Prefontaine Classic) in Eugene, Oregon.

[21] At the time, this was the fourth fastest men's 3000m performance in history, behind Ingebrigtsen's 7:23.63, Hicham El Guerrouj's 7:23.09, and Daniel Komen's world record of 7:20.67.