Ó Beaglaoich first played Gaelic football to a high standard as a schoolboy at Pobalscoil Chorca Dhuibhne. He was part of the school team that won back-to-back Hogan Cup titles in 2014 and 2015, with Ó Beaglaoich lining out as joint-captain for the latter victory.[1][2] He later played with University College Cork, and was part of the Sigerson Cup-winning team in 2019.[3]
By that stage, Ó Beaglaoich had also progressed to adult level with the An Ghaeltacht club, having earlier enjoyed success in the under-21 grade. He won a Kerry IFC title in 2017, before later claiming a Munster Club IFC medal after a defeat of St Senan's in the final.[4][5]
Following his first season with the under-21 team, Ó Beaglaoich was drafted onto the senior team in 2016. He won the first of seven Munster SFC medals in eight seasons that year.[8] Ó Beaglaoich was at left wing-back when Kerry were beaten by Dublin in the 2019 All-Ireland final replay.[9] He won three consecutive National League medals from 2020 to 2022, having earlier won the title as a member of the extended panel in 2017. Ó Beaglaoich won an All-Ireland SFC medal after a defeat of Galway in the 2022 final.[10]