In March 2017 he received a heavy injury while training with Bulgaria and returned at the end of 2019, but was forced to retire two years later, aged 34, due to ongoing problems.

Born in Pernik, Stoyanov began his career with the local club Metalurg, but joined the CSKA Sofia Academy in 2000, when he was 13.

[1] Stoyanov played four seasons for CSKA, but before he signed his first professional contract with the club, he decided to join Naftex Burgas.

[citation needed] Stoyanov started his first 2005–06 season in the senior squad as third-choice goalkeeper, behind Svilen Simeonov and Ivan Čvorović.

On 27 August 2014, Stoyanov kept a clean sheet in the 1–0 home win over Steaua București, but was sent off in the 119th minute of the match for fouling the advancing Fernando Varela and denying a goalscoring opportunity.

[8] On 1 October 2014, in Ludogorets' home debut in the 2014–15 Champions League group phase against the current holders Real Madrid, Stoyanov managed to save one of the two Cristiano Ronaldo penalties, although his team eventually succumbed to a 1–2 loss.

[18] On 27 March 2023 it was announced that Stoyanov will play for the Tundzha 2006 Tenevo team in "B" Yambol Regional Group, the fifth and last division in Bulgaria.

[20] On 25 March 2016, Stoyanov made close to a dozen important saves, including one penalty from Cristiano Ronaldo, to help Bulgaria secure an unexpected 1–0 away win in a friendly game against Portugal.

The first was saved on 1 October 2014 in Ludogorets' Champions League group stage match against Real Madrid, lost 1–2, and the second in Bulgaria's friendly against Portugal, won 1–0.