[3] He made his senior debut for Slavia in a match of the Europa League against Polish club Zagłębie Lubin on 30 June 2016, coming on as a substitute for Georgi Yomov.

[4] A month later he made his Bulgarian First League debut in the opening game of the season against CSKA Sofia.

On 1 October Petko was joined by his twin brother Andrea Hristov in the central defense for the very first time against Vereya in the starting line-up.

[9] He made his unofficial debut for the club against Real Madrid on 24 August coming on as a substitute in added time for the Trofeo Bernabeu game.

[20] He made his debut for the Bulgaria national football team on 31 March 2021 in a World Cup qualifier against Northern Ireland.