[1] Born in Sparta, Laconia, Kanellopoulos started playing football in a youth team of local club Sparta FC, before joining Asteras Tripolis youth sector in 2014.

He made his debut in Super League Greece on 4 July 2020, as a late substitute in a 4–0 win against Volos.

[2] After spending two-and-a-half seasons with Asteras Tripolis, Kanellopoulos signed with Finnish champions HJK Helsinki on 14 January 2023, on a two-year deal with an option for an additional year.

[3][4] In the 2023 season, Kanellopoulos helped HJK to first win the pre-season Finnish League Cup tournament, and ultimately to win the Finnish championship title, which was the fourth championship in a row for the club.

Kanellopoulos also made 13 appearances in the HJK's 2023–24 European campaign, in which the club qualified to the UEFA Europa Conference League group stage.