The club finally won the South-East V group during the 2013/14 season, achieving promotion to professional football for the first time.

During the same year, Sozopol reached the Round of 16 of the 2013–14 Bulgarian Cup, losing 8–1 on aggregate to Litex.

They finished their first B Group season in 6th place out of 16 teams, and expanded their stadium by building a South Stand, bringing the total capacity to 3,500.

During the 2015–16 Bulgarian Cup, the team reached the quarterfinals for the first time, beating OFC Etar Veliko Tarnovo in the Round of 16 and A Group member PFC Botev Plovdiv in the 1/8 finals.

They were eventually knocked out after a 3–0 defeat to CSKA Sofia, but finished the 2015–16 season in 4th place in the B Group, a record position for the club.