After a 120-goal spell at ElPozo Murcia FS he began playing full football with Ranero CF, scoring 57 and 84 goals in his respective seasons before joining FC Barcelona.

[3] Mir's 32 goals at La Masia earned him a return to his native region and Real Murcia, where a 45-goal haul led to the attention of Valencia CF.

[7] On 24 November 2015, Mir was called up to the main squad by manager Nuno Espírito Santo for a La Liga game against UD Las Palmas;[8] he was an unused substitute in the 1–1 draw at the Mestalla Stadium.

[9] He made his professional debut on 25 November, starting in a UEFA Champions League group stage match away to Zenit Saint Petersburg,[10] being substituted for Santi Mina in the 56th minute of an eventual 2–0 defeat.

[17] He began the first half of the 2017–18 season for Valencia B in good form, scoring 15 goals in 19 games, attracting interest from Real Madrid and Wolverhampton Wanderers.

[19] He made his debut three days later in the FA Cup third round at home to Swansea City, playing the last 13 minutes of a goalless draw in place of Léo Bonatini.

[32] The move collapsed for financial reasons, and a late approach by A.C. Milan for a loan with obligatory purchase was rejected due to a lack of remaining forwards at Sevilla.

[35] On 31 July, he scored an injury-time equaliser against the Ivory Coast to take their quarter-final to extra-time, in which he added two further goals to complete a hat-trick as Spain won 5–2.