Kallaste came through the Flora youth system. He made his debut in the Meistriliiga playing for Flora affiliated Warrior on 12 March 2006, in a 0–6 away loss to Maag Tartu. In July 2006, Kallaste moved to Flora's first team.[1] He made his debut for the club on 9 July 2006, in a 0–1 home loss to Levadia.
In July 2008, Kallaste joined Tulevik on loan until the end of the season.
Nõmme Kalju
On 6 January 2010, Kallaste signed a three-year contract with Nõmme Kalju.[2] He made his debut for the club on 9 March 2010, in 1–0 home victory over Tulevik. Kallaste helped Nõmme Kalju win the Meistriliiga title in 2012.[3][4] From 8 May 2010 to 20 July 2013, Kallaste played every single minute of 116 consecutive league matches, earning himself the nickname Raudmees (Iron Man).[5]
Górnik Zabrze
On 22 December 2015, Kallaste signed for Polish club Górnik Zabrze on a one-and-a-half-year deal, with an option to extend the contract for another year.[6] He made his debut in the Ekstraklasa on 13 February 2016, in a 0–3 away loss to Cracovia. Górnik Zabrze were relegated at the end of the 2015–16 season and on 25 June 2016, Kallaste was released from his contract by mutual consent.[7]
Korona Kielce
On 27 June 2016, Kallaste signed a two-year contract with Korona Kielce.[8] He made his debut for the club on 17 August 2016, in a 0–4 away loss to Zagłębie Lubin. Kallaste scored his first Ekstraklasa goal on 25 November 2017, in a 3–2 home win over Legia Warsaw.[9]
GKS Tychy
On 17 June 2019, Kallaste signed for I liga side GKS Tychy on a one-year deal, with an option to extend his contract for another year.[10]
On 1 November 2012, Kallaste was named in Estonia's squad for a friendly match against Oman on 8 November 2012, and made his senior international debut in the 2–1 away win.[11][12]
Personal life
Kallaste was born Ken Akerta, but changed his last name to Kallaste in 2006. He is the son of former professional footballer and Estonian international Risto Kallaste.[13]