He made his senior debut in 2008–09, playing two games with the reserves in Segunda División B and subsequently appearing in a further two full seasons in that level; it was during this time he formed a long-lasting friendship with future Russian national team player Denis Cheryshev.

[4] On 23 April 2011, Nacho made his first-team – and La Liga – debut, starting as a left back in a 6–3 away win against Valencia and playing in the entire match.

[citation needed] On 2 September 2012, main squad manager José Mourinho announced that Nacho, along with Álvaro Morata and Jesús, would be promoted to the first team but continue to play with Castilla.

[13] Benefitting from injuries and suspensions to teammates, he was the most utilized player in the centre-back position as the club won its first national championship in five years;[14][15][16][17] he added four matches in the Champions League, again conquered by his team.

[19] During that year's Champions League he made eight appearances while scoring one goal,[20] when Madrid won their third consecutive and 13th overall title in the tournament; in the decisive match against Liverpool, he featured at right-back after replacing the injured Dani Carvajal late into the first half of an eventual 3–1 win in Kyiv.

[29] On 4 May 2024, he clinched his fourth La Liga title with Real Madrid following a 3–0 victory over Cádiz, thus matching Marcelo, Karim Benzema and Luka Modrić's record as the club's most decorated player with 25 trophies.

[30] A month later, on 1 June, he captained his team in a 2–0 win over Borussia Dortmund in the Champions League final, as they clinched their 15th title in the competition making him one of the 5 players to have lifted the European most prestigious trophy a record of 6 times.

[36] On 2 September 2013, Nacho was called up to the Spain senior team for the first time, replacing the injured Iñigo Martínez in the squad for a friendly match against Switzerland.

[39] He started the team's opening Group B game against Portugal at right-back on 15 June, scoring his first international goal with a curled shot from 30 meters in a 3–3 draw.

[47] He eventually featured in Spain's victory against England in the final, becoming one of 12 players who won both youth and senior Euro titles, alongside his teammates Mikel Merino, Ferran Torres, Álvaro Morata and Rodri.

He is seen as a reliable full-back option due to his skills on the ball and penchant for making forward runs down his flank; a fast and agile defender who is known for his work rate, endurance and strength in the air despite not being particularly tall for his position.