He played college football for the BYU Cougars and was selected by the Falcons in the fifth round of the 2022 NFL draft.

[5] He played in all 13 games that season recording 26 tackles and 0.5 sacks on defense and 119 yards on 17 carries on offense.

[7][8][9] On December 28, 2021, Allgeier announced that he would forgo his remaining two years of eligibility and enter the 2022 NFL draft.

[15] In Week 5, Allgeier made his first career start, due to a knee injury to running back Cordarrelle Patterson.

[24] Allgeier scored two rushing touchdowns in the Falcons' 2023 regular season opener, a 24–10 victory over the Panthers.