Born in Cascais, Varela started playing professionally with G.D. Estoril Praia in the second division, being loaned to lowly U.D. Rio Maior for one year during his spell. In January 2009 he moved to C.D. Trofense, as the northern club was playing for the first time in the Primeira Liga; he managed to appear regularly during the season, but they were relegated. In the summer of 2011, after two additional second level seasons with Trofense, Varela signed for C.D. Feirense, returned to the top flight after a 22-year absence. In the following campaign he played all league games as a starter, notably scoring twice against S.L. Benfica on 28 January 2012 in a 1–2 loss where he also committed a penalty, and his team would again drop down a tier.
Romania
On 29 May 2012, Varela signed a three-year contract with Romanian side FC Vaslui. On 3 September of the following year he joined FC Steaua București also from Liga I, after agreeing to a three-year deal for a €1.25 million transfer fee. At the end of 2014–15, Málaga CF showed interest in acquiring Varela, but Steaua rejected the Spaniards' €6 million offer. He appeared in 47 matches across all competitions, in an eventual double conquest.
PAOK
On 23 July 2016, Varela, who had less than six months left on his contract, moved to the Superleague Greece with PAOK FC for three years and a €1.4 million fee. He scored his first goal in the 2017–18 season on 12 February 2018, heading home in a 3–0 win against Athlitiki Enosi Larissa F.C. at the Toumba Stadium. On 21 May 2019, Varela declined the club's contract renewal offer.
International career
Portuguese-born, Varela opted to represent Cape Verde internationally, his debut coming in 2008. On 24 May 2010, he appeared in a friendly in Covilhã with Portugal – which was preparing for the FIFA World Cup in South Africa – playing the entire match as the minnows managed a 0–0 draw. The Blue Sharks were disqualified from the 2014 World Cup when it was revealed that Varela had played in a qualifying match against Tunisia, despite not completing a four-match suspension for a red card he had received against Equatorial Guinea on 24 March 2013. That game was later rendered invalid by FIFA as a result of Equatorial Guinea fielding ineligible Emilio Nsue, but Varela's disciplinary record stood.
