A product of Sporting CP's youth system, Semedo was born in Setúbal and made his professional debut with modest Casa Pia AC, in the Lisbon area.

[4] He made his competitive debut in the Coppa Italia, but would only appear three times in the league, the first as a late substitute in a 3–1 away loss against AC Milan on 21 April 2007.

[9] However, manager Chris Powell could not offer him assurances that he would be a key member in the following season, as he aimed to create a more fluid midfield, and so, on 7 July, the player joined Sheffield Wednesday also of the English third tier, again as a free agent.

[16] In 2023, a mural by local artist Pete McKee inspired by Semedo's celebration of Chris O’Grady's winning goal in the 2012 victory over city rivals Sheffield United was unveiled close to Wednesday's ground.

[24] During his formative years at Sporting, Semedo became a close friend of Cristiano Ronaldo, later of Manchester United, Real Madrid, Juventus FC and Portugal fame.