|Full name||Simeon Nenchev Slavchev|
|Date of birth||25 September 1993|
|Place of birth||Sofia, Bulgaria|
|Height||1.85 m (6 ft 1 in)|
|2011||→ Chavdar Etropole (loan)||14||(0)|
|2014–2015||Sporting CP B||3||(0)|
|2015||→ Bolton Wanderers (loan)||1||(0)|
|2015–2016||→ Apollon Limassol (loan)||21||(1)|
|2016–2017||→ Lechia Gdańsk (loan)||23||(0)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 08:59, 25 May 2017 (UTC).
‡ National team caps and goals correct as of 22:13, 27 April 2017 (UTC)
Slavchev started his career at home-town club Septemvri Sofia, joining their youth system as a six-year-old. In the 2006–07 season, he became a goalscorer for their youth team. In 2007, Slavchev joined Slavia Sofia and was part of the side that won the Bulgarian U-15 Championship in the 2007–08 season.
Slavchev joined the Litex's first team in October 2010. He made his debut during the 2010–11 season, on 31 October 2010 in a 2–0 home win over Slavia Sofia, coming on as a substitute for Hristo Yanev.
Loans to Bolton, Apollon and Lechia
On 2 February 2015 Slavchev joined Bolton Wanderers until the end of the season. He made his debut for the team in the English Championship on 7 February 2015 in a match against Derby County.  It was his only match for Bolton after Slavchev got injured and was ruled out until the end of the season. 
On 11 August 2015, Slavchev joined the Cypriot team Apollon Limassol on loan for the 2015–16 season.  He made his debut on 23 August 2015, scoring the winning goal after added time.  On 19 May 2016 Apollon won the Cypriot Cup. 
Slavchev had an injury at the end of the 2015-2016 season. Sporting decided to loan him out in order for him to gain more experience and to reach full fitness. On 17 August 2016, Slavchev joined Polish club Lechia Gdańsk, on a season-long loan, where he would play alongside fellow Bulgarian footballer, Milen Gamakov. Slavchev made his debut for the team on 9 September 2016, playing the full 90 minutes in a 1-0 win against KS Cracovia.
- As of 6 June 2017
|Club performance||League||Cup||League Cup||Continental||Other||Total|
|Litex Lovech||2010–11||A Group||1||0||0||0||–||0||0||0||0||1||0|
|Chavdar Etropole (loan)||2011–12||B Group||14||0||2||0||–||–||–||16||0|
|Litex Lovech||2011–12||A Group||0||0||0||0||–||0||0||0||0||0||0|
|Sporting CP||2014–15||Primeira Liga||0||0||0||0||2||0||0||0||–||2||0|
|Bolton Wanderers (loan)||2014–15||Championship||1||0||–||–||–||–||1||0|
|Apollon Limassol (loan)||2015–16||First Division||21||1||5||1||–||0||0||–||26||2|
|Lechia Gdańsk (loan)||2016–17||Ekstraklasa||23||0||0||0||–||0||0||–||23||0|
- As of 10 October 2016
In September 2009, he was called for Bulgaria U17 by coach Atanas Zhelev and took part in the UEFA U-17 European championship. In 2011, he was called up for the UEFA U-19 European Championship. In 2012, he got his first call-up for the national youth team by coach Michael Madanski.
In 2013, he was called up for Bulgaria by Lyuboslav Penev for the 2014 World Cup qualification games against Malta and Denmark. On 15 October 2013, in the last match for the qualifications for the 2014 FIFA World Cup against the Czech Republic, he made his debut for the first team as a substitute.
On 25 March 2016, Slavchev came on as a substitute during the magnificent 0-1 away win over Portugal. On 13 November 2016, he played the full 90 minutes in the 1:0 win over Belarus in a 2018 World Cup qualifier.
- Litex Lovech
- Apollon Limassol
- "Simeon Slavchev". winner.bg.
- "Симеон Славчев – лидерът на третата вълна таланти от Литекс". winner.bg.
- "Simeon Slavchev Facts". Footballdatabase.eu.
- Sporting oficializa empréstimo de Slavchev ao Lechia Gdansk‚ desporto.sapo.pt, 17 August 2016
- "Славия стана шампион на България при децата" (in Bulgarian). topsport.bg. 10 July 2008.
- "Литекс попълва състава с юноши" (in Bulgarian). sportni.bg.
- "Литекс сам на върха след 2:0 над Славия" (in Bulgarian). sportni.bg. 31 October 2010.
- "Литекс се отпуши, гази Черно море с 4:1" (in Bulgarian). pfclitex.com. 4 November 2012.
- "Sporting sign promising Bulgaria midfielder Slavchev". eurosport.com. 19 May 2014.
- "Wanderers sign Simeon Slavchev on loan from Sporting Lisbon". bwfc.co.uk. 2 February 2015.
- Derby County VS. Bolton
- Симеон Славчев за Sport7: Връщам се в Спортинг
- ОФИЦИАЛНО: Симеон Славчев подсили кипърци
- APOLLON VS. ARIS
- Симеон Славчев ликува с Купата на Кипър
- Представиха Симеон Славчев в новия му отбор
- Победен дебют на Симеон Славчев в Полша
- Български национал на проби при Хари Реднап
- "Slavchev Statistic". soccerway.com.
- "Младежите направиха равен с Македония в контрола". gong.bg.
- "Пенев извика играчи на Славия, Локо Пд и талант на Литекс в националния". sportal.bg.
- Браво, момчета! България наказа Португалия, а Кристиано ще запомни Владо Стоянов (видео)
- "Bulgaria NT vs. Belarus NT 1:0". flashscore.com. 13 November 2016. Retrieved 6 March 2017.
- "Иван Иванов е футболист на годината" (in Bulgarian). sportni.bg. Retrieved 2013-12-28.
- "Вижте всички детайли по трансфера на Славчев, "Литекс" уреди контрола със "Спортинг" (in Bulgarian). Retrieved 2014-05-20.