Born in Montevideo on 1 October 1993, Nico Lopez is one of the most promising youngsters coming out of Uruguayan football. A quick forward with good technique, Nico came through the youth team at Nacional and immediately caught the eye, in spite of his small number of games with the first team. Walter Sabatini was amazed by his style of play and brought him to Roma in the 2012 January transfer window, where he joined the Primavera squad, and he has already played a key role in Alberto De Rossi;s side. Lopez joined the first team on their July training camp, giving coach Zeman another option going forward.

On 24 April 2011, after being promoted as part of the first team under head coach Juan Ramón Carrasco, López made his debut at the age of 17 in a league game against Central Español, promptly scoring also his first senior goal.

In August 2011, López was involved in a feud with Nacional, after his father revealed the player was in Italy in order to hold talks with a number of unspecified Serie A sides, leading his Uruguayan club and the national federation to consider potential actions to the FIFA against the player. He was subsequently acquired by Roma in the January 2012 transfer window, and then included in the Primavera under-19 squad for the rest of the season.

López was taken into consideration as a first team player by new head coach Zdeněk Zeman, who included him in the senior roster for the pre-season camp and then featured him in a number of friendly games. López made his first team debut on 26 August 2012, replacing captain Francesco Totti in the final minutes of the first game of the Serie A season, a home match versus Catania, and promptly scored an injury time equaliser (the game ended 2–2). He also started the round of 16 cup match against Atalanta.