In July 2012, Rojo moved from Spartak Moscow to Sporting CP for £3. 5 million, signing a four-year contract. Rojo made his Primeira Liga debut for Sporting on 19 August 2012, playing the entire match and receiving a yellow card in a 0–0 draw with Vitória de Guimarães. He received his first red card for Sporting in a league match against Porto on 7 October 2012, picking up two cautions within three minutes as Sporting fell to a 2–0 defeat. He scored his first goal for Sporting on 28 April 2013, netting the winner against Nacional. Rojo played mostly at centre-back in his first season in Portugal, occasionally at left-back, as the team had a comparatively bad season, finishing seventh in the league.