She won the gold medal at the 2024 Summer Olympics in the 100 metres event, setting a new national record of 10.72s in the final.

She also captured silver in the 2018 Youth Olympic Games in Buenos Aires, Argentina behind Nigeria’s Rosemary Chukwuma.

The same month, she ran a wind-aided 10.80 s (+2.2 m/s) at the NCAA West Preliminary Round - the fastest time ever recorded under any conditions at the event.

She won the 2022 NCAA Division I 100 m/m title in 11.02 s (+0.2 m/s) the day after her 21st birthday, completing an unbeaten collegiate season in that event.

She next went on to win her event at the inaugural Caribbean Games in Les Abymes, Guadeloupe in a time of 11.07 seconds (−0.2 m/s).

She also achieved the second-fastest all-time collegian mark in the 200 m of 22.26 s, behind only Abby Steiner, to become the fourth-fastest woman of all time.

[11][12] Julien went on to compete in the women's 100m race at the Istvan Gyulai Memorial, crossing the finish line with a time of 10.89 seconds,[13] resulting in a victory over sprinter Sha'Carri Richardson.

[19] Alfred ran a lifetime best and equalled the stadium record in the women's 100 metres at the Racers Grand Prix in Kingston, Jamaica on 1 June 2024, running 10.78 seconds.