Independiente Born in
Mar del Plata, Martínez started his career playing for
Independiente's youth team. In 2009, shortly after his 17th birthday, he was invited to trial at Arsenal, and was initially offered a youth contract.
Arsenal 2010–2019: Loan moves and fringe appearances in 2018 After impressing in a trial and being approved for a work permit, Martínez was formally registered as an Arsenal player in July 2010. After injuries to
Ryan Clarke and
Wayne Brown, and the termination of
Connor Ripley's
loan, Martínez went on emergency loan to
Oxford United, making his debut in the
Football League in their final game of the season against
Port Vale in
League Two on 5 May 2012; Port Vale won 3–0. Later that year, Martínez was named on the Arsenal substitute bench for their fixtures away at
Stoke City on 26 August and against
Liverpool on 2 September, as cover for the injured
Wojciech Szczęsny and
Łukasz Fabiański, respectively. On 26 September, he made his Arsenal debut in a 6–1 home win against
Coventry City in the third-round of the
League Cup. He made his second Arsenal appearance in the following round in a
7–5 win away to
Reading. Martínez subsequently transferred to
Championship club
Sheffield Wednesday on an emergency 28-day loan on 15 October 2013. He made his debut for Wednesday on 23 November, against Yorkshire rivals
Huddersfield Town. Martínez's loan was eventually extended until the end of the season. After returning to Arsenal, Martínez was an unused substitute as Arsenal won the
2014 FA Community Shield on 10 August, with a 3–0 win over
Manchester City at
Wembley Stadium. He made his debut in the
Champions League soon after, helping Arsenal defeat
Anderlecht 2–1 in the group stage. He then made his Premier League debut as a second-half substitute, replacing the injured Szczęsny against
Manchester United at the
Emirates Stadium on 22 November. With injuries to backup goalkeeper
David Ospina, Martínez played his second Champions League game on 26 November, keeping a
clean sheet in a 2–0 victory over
Borussia Dortmund. His "faultless" performance in the match led to him being named in the UEFA Team of the Week. He made his first Premier League start on 29 November against
West Bromwich Albion, and also started against
Southampton four days later; he kept two clean sheets as Arsenal won both matches 1–0. On 20 March 2015, Martínez joined Championship club
Rotherham United on an emergency loan until the end of the season. He made his debut the following day against
South Yorkshire rivals Sheffield Wednesday, losing 3–2. Despite the poor start, Rotherham finished the season strongly with Martínez in goal, only losing 1 of the last 6 games and avoided relegation. Despite only playing a dozen games from the club, his reflex saves in important games made him a fan favourite. On 2 August, Martínez was an unused substitute as new signing
Petr Čech played for Arsenal in the
2015 Community Shield, a 1–0 win over
rivals Chelsea. On 11 August, he joined Championship club
Wolverhampton Wanderers on a season-long loan. After making 15 appearances in the opening months of the campaign, he suffered a thigh injury that kept him out of contention for several months and was unable to regain his starting place afterwards. He spent the 2016–17 season at Arsenal and played five matches during the campaign, including two Premier League appearances against
Crystal Palace and
West Ham United. On 2 August 2017, he joined
La Liga club
Getafe on a season-long loan, and on 23 January 2019, he was loaned to Championship club Reading until the end of the season. At Reading, Martínez made his debut on 29 January against
Bolton Wanderers, and won the
man of the match award against
Aston Villa a few days later.
2019–2020: Breakthrough and departure With
Bernd Leno being taken off injured during the first half of Arsenal's defeat to
Brighton & Hove Albion on 20 June 2020, Martínez came off the bench to make his first Premier League appearance since the 2016–17 season. This led to Martínez seeing out the season as first choice goalkeeper at the club and was highly commended for a string of stellar performances, with former Arsenal striker
Ian Wright describing him as "commanding" and as having played "brilliantly" during his extended spell in the team. On 1 August, Martínez was selected to start in the
FA Cup Final against Chelsea, making some crucial saves to help Arsenal win their 14th FA Cup; after lifting the trophy he was visibly emotional and reduced to tears. Martínez started in the
2020 Community Shield against Liverpool on 29 August, which Arsenal won on penalties. Following the match, there was much speculation that Martínez would leave the club with Bernd Leno returning and the player himself stated that he either wanted to stay at the club and be first-choice keeper or leave on a permanent basis. With reported interest from a number of clubs, including Aston Villa and Brighton & Hove Albion, Martínez was left out of the squad to face
Fulham on the opening day of the
league season.
Aston Villa On 16 September 2020, 28-year-old Martínez transferred to fellow Premier League club
Aston Villa in a deal worth up to £20 million. He signed a four-year contract. On 21 September, Martínez made his debut for Villa, saving a penalty from
John Lundstram in a 1–0 home win against
Sheffield United. In his first season at Aston Villa, Martínez equalled
Brad Friedel's club record for clean sheets in a Premier League season, with 15. He was also named Aston Villa Supporters' Player of the Season. On 21 January 2022, Martínez signed a three-year contract extension which will see him contracted to Villa until the end of the 2026–27 season. On 27 July, ahead of the new season, Martínez was named one of the two Aston Villa
vice-captains, alongside
Diego Carlos. On 1 April 2023, Martínez made his 100th Premier League appearance for Aston Villa in a 2–0 away victory over Chelsea. That clean sheet was Martínez's 34th, which broke the club record of the most clean sheets in a goalkeeper's first 100 games – which was previously set at 33, by both
Mark Bosnich and Brad Friedel. On 18 April 2024, he saved two penalties in a 4–3 victory over
Lille following a 3–3 draw on aggregate, which qualified his club to the
Conference League semi-finals. On the eve of the
2024–25 season, Martínez chose to switch his shirt number from the traditional number 1, to the number 23 shirt worn for Argentina during his successful cup campaigns with them. On 21 August 2024, Martínez signed new long-term contract with Aston Villa, lasting until 2029. Martínez won the
Premier League Save of the Month award for December 2024, his first time winning the award, for a goal line save against
Nottingham Forest in a 1–2 loss. Martínez stopped a header from
Nicolás Domínguez that went past him by reaching behind him and swatting it away as it was on the goal line. During Aston Villa's final game of the season against Manchester United, Martínez was given a straight red card and sent off in the first half after making a challenge on
Rasmus Højlund outside the box. In November 2025, Aston Villa manager
Unai Emery confirmed that he had stripped Martínez of his vice-captaincy, giving the role to
Ezri Konsa. Emery did not elaborate, other than saying he had had a conversation with Martínez, although there was speculation that the decision was related to Martínez's failed attempts at generating a move away from Villa the previous summer transfer window. == International career ==