A native of Tallinn, Kullamäe started his career in 2014 in the ranks of Audentes, which at the time played in the Estonian first division Korvpalli Meistriliiga (KML).

[1] After helping his team advance to the league finals, Kullamae made his debut in the top-tier Basketball Bundesliga (BBL) in the following 2017–2018 season.

[4] Under the terms of his contract, Kullamäe spent his first year playing on loan for Palma of the LEB Oro, where he was one of the leading players with 16.0 points per game.

[6] On 30 November 2022, Kullamäe recorded 24 points (9/12 FG), six rebounds, seven assists and a 28-point PIR in a 104–98 home win over Cedevita Olimpija.

Kullamäe made his debut for the Estonian national team on 25 February 2018, in a 2019 FIBA Basketball World Cup qualifier against Israel, scoring 8 points in a 78–62 home victory.