In July 2019, Ostrander announced her plans to forgo her final season of NCAA eligibility and begin running professionally.

[citation needed] Ostrander graduated from Kenai Central High School in 2015 and matriculated to Boise State University.

[citation needed] Later that month, she anchored her Broncos distance medley team to a first-place finish at the Mountain West Indoor Track and Field Championships.

[citation needed] In November, Ostrander finished second in the 6 kilometers in the NCAA West Region Championships, with a career best time of 19:16.5.

On May 10, Ostrander finished less than a second behind Karissa Schweizer in the 2018 NCAA Division I Indoor Track and Field Championships at 3000 meters, running 8:54.35.

[17] On January 26, Ostrander broke the Boise State school record for the mile at the University of Washington Indoor Meet, running 4:35.79.

[19] On May 2, she returned to the steeple at the Payton Jordan Invitational in Stanford, California, to win 0.05 seconds ahead of New Mexico State's Adva Cohen.

[25] On April 2, 2020, Ostrander received platelet-rich plasma (PRP) therapy to help accelerate the healing of her torn achilles tendon.

[25] The same year, Ostrander began a volunteer coaching position with the NCAA DII distance running program at Seattle Pacific University.

[32] On August 25, 2023, Ostrander was suspended for 4 months by the USADA after testing positive for canrenone, a banned substance that's often used as a masking agent, on March 30, 2023.

[36] In January 2025, Ostrander announced that she had signed a contract with Oiselle, and would continue to compete in track, road, and trail competitions.

[38] [39] In 2018, NCAA commentator Jill Montgomery referred to Ostrander as the "baby-faced assassin", and said she looked like she still played with "Barbie Dolls".

"[50] In 2019, Ostrander wrote, "This year, the commentators found it necessary to state (incorrectly I might add) my height and weight multiple times.

"[50] ESPN subsequently responded with a statement regarding the comments in question, saying: "We greatly appreciate Allie bringing this important conversation to light.

[51] Ostrander frequently competes in the Mount Marathon Race in Seward, Alaska, which she began running in grade school.

[52] In 2015, in her first senior race, Ostrander finished under the standing 25-year-old female record, but was beaten by world skyrunning champion Emelie Forsberg.

[43] Her domestic partner is Spencer Brown, a former Brooks Beasts middle-distance runner and host of YouTube channel The Athlete Special.