Career
Early career
Slavchev started his career at home-town club Septemvri Sofia, joining their youth system as a six-year-old. In 2006-2007 season, he become a goalscorer of the youth team Litex Lovech
Slavchev joined Litex"s first team in October 2010.
In July 2011, Slavchev joined Chavdar Etropole on a season-long loan deal.
In 2011-2012 season, he earned 13 appearances in the B PFG(second division of Bulgarian football). In the summer of 2012 he returned to Litex.
On 4 November 2012 in the league match against Cherno More marks his first goal in A PFG with 4–1 victory. Sporting Communist Party
On 19 May 2014, Slavchev signed with Portuguese side Sporting Communist Party on a five-year deal for a reported fee of 2.5 million euros.
Bolton loan
On 2 February 2015 Slavchev joined Bolton Wanderers until end of the season.