KSE was founded in 1912 and is the second team from Covasna (a county with a majority of Székely ethnics) as ranking in the Romanian football, after Sepsi OSK Sfântu Gheorghe.

At the inaugural meeting, the members unanimously elected Dr. Dénes Molnár (lawyer) as the president, Gyula Séra (public notary) and Kálmán Mina (chief of police) as the vice-presidents.

In August 1940, after the signing of the Second Vienna Award, Hungary annexed northern Transylvania, including Târgu Secuiesc and KSE was distributed in one of the Nemzeti Bajnokság II (Hungarian second division) series, the best rank in the history of the club, until now.

[2] Between 1941 and 1945, the club played only in the third tier, Nemzeti Bajnokság III, then after the return of Târgu Secuiesc between the borders of Romania, the team disappeared again from the national leagues.

At the end of the 2016–17 season, KSE won Covasna County League, then the promotion play-off against Pro Mureșul Toplița (9–0 on aggregate) and returned, once again, in the Liga III.

[1] Liga IV – Covasna County Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.