Morgan acted in Welsh-language soap opera Pobol y Cwm as Aaron Monk, a character whose mother had bipolar disorder.[1] In 2023, he was cast on Waterloo Road as Myles Massey, a 16-year-old released from a football academy; Morgan said he empathised with the character, having been released by Cardiff City at age 14.[2] Morgan said of the character "I can imagine most people are absolutely going to despise him. Just for the record, this isn't me. This is a character I'm playing".[2] In June 2024, he debuted on Emmerdale as troublemaker Josh Cope.[1] The character harassed trans man character Matty Barton, whose actor Ash Palmisciano said "I think the audience will really dislike [Josh Cope] but that's because [Osian Morgan] nailed it and did such a good job".[3]
In 2026, Morgan appeared in Power: The Downfall of Huw Edwards as "Ryan Davies" (pseudonym), a 17-year-old who was groomed by newsreader and sex offender Huw Edwards. Morgan said that the series was pitched to him as Untitled Welsh Project with a fictional antagonist named Stuart who was not a newsreader. Having previously played dominant villains, Morgan enjoyed playing a vulnerable character.[4]