Krastev made his senior debut for Slavia on 7 December 2015, coming on as a substitute for Daudet N'Dongala in a 3–0 win against Lokomotiv Plovdiv.

[3] He scored his debut goal for the team in the league on 15 April 2017 in a match against Montana, won by Slavia with 4:3.

[4] On 24 January 2018, Krastev signed a 4-year contract with the Serie A team Bologna with the transfer fee reported to be a 1.5 million euro.

[8] He became a hero for the team in the next match against Bosnia and Herzegovina U19, scoring 2 goals for the 3–1 win and qualifying Bulgaria for the knockout phase.

[9] He made his debut for Bulgaria national football team on 2 September 2021 in a World Cup qualifier against Italy that ended in a 1–1 away draw.