The winger joined the Shamrock Rovers U19 squad for the 2015 season.
He then signed for Bohemians U19s for 2016. Having played for the Gypsies first team, Dean made a loan move to Cabinteely in 2017.
He made his debut against UCD on 28 July 2017. That move was made permanent in 2018.
He then switched to Athlone Town at the start of the 2019 campaign. But Casey returned to Cabinteely in July 2019.