In August 2011, Neira joined
Lanús on a one-year loan from
Gimnasia y Esgrima de La Plata, with an option to sign permanently. Lanús did not choose the option, and in 2012 Neira signed another one-year loan with the Spanish team
Valladolid. On 31 July 2013, he joined the Mexican
Ascenso MX side
Estudiantes Tecos. The following years he played mostly in Mexico.
OFI On 29 June 2018, he signed a year contract with newly
Super League club
OFI. In his
debut season with the Greek club, Juan appeared in 24 matches, scoring 6 goals and giving 1 assist. On 4 July 2019, he signed a contract renewal until the summer of 2021. His first goal for the
2019–20 season came in a 3–1 home win against
Asteras Tripolis, on 29 September 2019. On 6 October 2019, he scored in a triumphant 4–1 home win against
Panionios. On 4 December 2019, Neira scored a brace in a 4–0 home win against
Kavala, securing his team's spot in the round of 16 of the
Greek Cup. On 4 January 2020, he scored in a 2–1 home loss against
Volos. On 4 July 2020, he scored with a nice left-footed strike in a 2–2 home draw against
PAOK. He scored in the
2020–21 season's opener, a 1–1 home draw against
Panetolikos, on 12 September 2020. On 23 November 2020, he scored with a penalty in an emphatic 4–1 away win against Volos. The following week, he scored with a penalty in a 2–1 win against
PAS Giannina, the first at home for the season. ==International career==