Sebastian Kóša

Nitra

Kóša made his professional Fortuna Liga debut for Nitra against ViOn Zlaté Moravce on 13 June 2020.

Spartak Trnava

Kóša joined Spartak Trnava on 18 July 2020. He scored his first league goal against AS Trenčín the same year on 25 October, breaking Josef Adamec's record as Spartak Trnava's youngest goalscorer at the age of 17 years, 1 month, and 11 days. In February 2022, Kóša was named the Best Player of Slovakia in the U19 category at Grassroots Football Gala hosted by the Slovak Football Association.

Real Zaragoza

On 24 August 2024, Kóša signed a four-year contract with Spanish Segunda División side Real Zaragoza, becoming their tenth signing of the transfer window. Initially kept out of the starting line-up, Kóša only made a substitute appearance before fellow central defender Lluís López was suspended after receiving a red card, leading to his first start in October 2024. He made just two league starts for the club before sustaining an ankle fracture in a Copa del Rey match against L'Hospitalet at the end of the same month.

Košice (loan)

Following injuries and lack of game time, it was announced that Kóša would be returning to Slovakia to join FC Košice of a half-year loan.

At the age of 17 in 2021, Kóša became the youngest player of the Slovakia U21 national team, playing the full match against Lithuania and Northern Ireland. In December 2022, Kóša received his first call-up to the Slovakia senior national team for a training camp at NTC Senec. His senior international debut came on 23 March 2024, coming on as a substitute in a 0–2 friendly loss to Austria. He was later named in Slovakia's UEFA Euro 2024 squad.

Club

As of matches played on 29 October 2025

International

As of match played 23 March 2024

Spartak Trnava

Slovak Cup: 2021–22, 2022–23 Individual

Slovak Super Liga U-21 Team of the Season: 2021–22