Halliday joined the Orlando City Development Academy in 2016, playing 90 games from under-16 up to under-19 level in four seasons.[3] In March 2020 he signed an academy contract with Orlando City B, the club's USL League One affiliate, ahead of the 2020 season.[4] In July 2020, Halliday signed an MLS homegrown contract.[5] He remained with OCB for the season, making his debut in the season opener, a 2–0 defeat to Tormenta FC on August 1.[6][7] On May 29, 2021, Halliday made his senior Orlando City debut starting in a 2–1 defeat to New York Red Bulls. In doing so he became Orlando City's youngest first team player at 18 years, 127 days, beating Tommy Redding's record set in August 2015 by 70 days.