Martínez was born inBahía Blanca. He followed in his father's footsteps to become a professional footballer, joining local sideLiniers, with whom he excelled at U–17 level.[3] In 2013, he scored 13 goals in the U–17 league and netted in the final of the National Cup, though Liniers ultimately lost onpenalties to Rosario.[4][5]
Martínez's form at youth level caught the attention ofRacing Club interim coach Fabio Radaelli who subsequently signed him in January 2014.[4] Soon after joining the club, Martínez began suffering from homesickness and wanted to return to his hometown. He was ultimately convinced by teammateBraian Mansilla to stay and went on to score 53 goals in 64 appearances for the club's reserve side.[3] In 2015, a deal was concluded between Racing Club and Spanish sideReal Madrid for Martínez's signature but he chose to remain in Argentina. Martínez's father, Mario later revealed that he chose to stay with Racing at the time as he was not ready to leave the club.[6] Hisleague debut followed on 1 November 2015 when he came on as a second-halfsubstitute forDiego Milito in a 3–0 win overCrucero del Norte.[7] On 17 April 2016, he wassent off for the first time in his career after picking up two bookings in the space of five minutes in a 2–2 draw withArgentinos.[3] He scored his first goal later that year, netting the opener in a 1–1 draw withHuracán in November.[3]
Following an injury to regular starting strikerLisandro López, Martínez assumed a more senior role for the2016–17 season, scoring 9 goals in 23 league appearances for the campaign.[3][8] He continued to lead the line for Racing during the first half of the following season and in December 2017 underwent a medical withLa Liga sideAtlético Madrid.[9] Reports followed that Martínez had signed for Atlético Madrid side but Racing later announced that he had signed a renewed contract which included an increased release clause. They also criticised their Spanish contemporaries for submitting him to a medical without their permission.[9][10] He ended the year with aman of the match performance, scoring once andassisting another in a 3–1 win overGimnasia.[11] On 27 February, he scored his secondhat-trick of the season when he scored three times on hisCopa Libertadores debut against Brazilian sideCruzeiro. Racing won the match 4–2.[12]
That same month, Martínez was linked with a transfer to Italian sideInter Milan and on 5 May Racing Club President Victor Blanco confirmed that the sale had gone through. Blanco indicated that Martínez was set to join Inter ahead of the2018–19 Serie A campaign but that he would attempt to keep him onloan until December 2018 in order for the striker to continue to participate in the Argentine side'sCopa Libertadores campaign.[13][14]
Martínez joined Inter on 4 July 2018 for a reported fee of €22.7 million and he signed a five-year contract with the club.[15] He made his unofficial debut ten days later and scored in a 3–0 friendly win over Swiss club,Lugano.[16] His full debut followed on 19 August when he started in a 1–0Serie A loss toSassuolo in the opening week.[17] He scored his first league goal againstCagliari, the opener of a 2–0 win atSan Siro on 29 September.[18]
Martínez scored his first European goal on 14 February 2019, netting a penalty to help Inter win againstRapid Wien, in the first leg of2018–19 UEFA Europa Leagueround of 32.[19] Following this match, he began to start in every match, profiting fromMauro Icardi's absence for personal reasons.[20] In his firstDerby della Madonnina match against city rivalsMilan, Martínez first assistedMatías Vecino's header before scoring himself a penalty in the second half, helping Inter to win 3–2;[21] Inter retook the third place in Serie A,[22] and also achieved the first league double over them since 2011–12 season.[23]
On 16 May 2023, he scored the only goal in a 1–0 victory over rivals Milan in theChampions League semi-final second leg, which secured a 3–0 win on aggregate for his club and qualification to theChampions League final for the first time since2010.[30] On 24 May, he scored a brace in a 2–1 victory overFiorentina, to achieve his second consecutiveCoppa Italia.[31]
Martínez, who became the club's captain followingSamir Handanović,[32] began the 2023–24 season, his sixth with the club, as the first choice striker, albeit once again without his strike partnerRomelu Lukaku after he returned to Chelsea finishing the end of his loan spell. He began the season with an immediate impact for Inter, scoring both goals in a 2–0 home win overMonza on the first match day,[33] and then scoring Inter's second goal the following week in another 2–0 win away againstCagliari.[34]
On 30 September 2023, after replacingAlexis Sánchez in the 55th minute of Inter's 4–0 win againstSalernitana, Martínez became the first player in Serie A history to score 4 goals as a substitute.[35] On 25 February 2024, Martínez scored twice in a 4–0 away league win againstLecce, the first goal was his 100th Serie A goal and the second was his 22nd league goal of the season (with only 23 games played), surpassing his personal record of most league goals in a season.[36] Martínez eventually won thecapocannoniere award in the 2023–24 season, finishing as the top scorer in Serie A with 24 goals.[37] He also won the Serie A MVP for the season.[38]
On 29 January 2025, he netted his first Champions League hat-trick, the first goal of which was a penalty, in a 3–0 victory overMonaco.[39] On 16 April, he netted his 150th goal for Inter in a 2–2 draw againstBayern Munich during theChampions League quarter-finals, in addition to becoming the first player to score for the club in five consecutive matches in the competition.[40][41] In the second leg of the semi-finals against Barcelona, he scored a goal and delivered an assist, contributing to a 4–3 victory after extra time and helping his team reach their secondChampions League final in two years.[42]
He was subsequently named in the squad for the World Cup which kicked off in May that year. In the build-up to the tournament, he suffered damage to his nasal cartilage after being struck by a knee in a warm-up match against Vietnam.[43] As a result of the injury, he started Argentina's opening match at the tournament againstEngland from the bench and was latersent off after video technology indicated that he had lashed out atFikayo Tomori. Upon doing so, he became the first ever player to be dismissed after a video referral, and Argentina ultimately lost the match 3–0.[43][44][45] On his return, he scored a brace in a 5–0 win overGuinea, though his goals were not enough to prevent Argentina from being eliminated from thegroup-stages.[43][46]
On 12 March 2018, Martínez received his first call-up for thesenior team for twofriendly matches againstItaly andSpain.[47] He made his debut against the latter on 27 March, coming on as a substitute forGonzalo Higuaín in a 6–1 defeat.[48] In May 2018 he was named in Argentina's preliminary squad for the2018 FIFA World Cup inRussia but was omitted from the final selection.[49][50] Later that year, he made his full debut in a 4–0 friendly win overIraq during which he also scored his first senior international goal.[51]
In May 2019, Martínez was included inLionel Scaloni's final 23-man Argentina squad for the2019 Copa América.[52] In Argentina's final group match againstQatar on 23 June, he scored the opening goal in a 2–0 win, which enabled them to advance to the knock-out stages of the competition.[53] On 28 June, in the quarter-finals of the tournament, Martínez scored the opening goal in an eventual 2–0 win overVenezuela with a back-heel in the opening ten minutes of the match; he was later namedMan of the match, and the victory enabled Argentina to advance to the semi-finals of the competition.[54]
On 10 September 2019, Martínez scored his first internationalhat-trick in afriendly againstMexico, which Argentina won, 4–0.[55]
On 28 June 2021, he scored Argentina's final goal in a 4–1 win overBolivia in his nation's final group match of the2021 Copa América.[56] On 3 July, he scored the second goal in a 3–0 win overEcuador in the quarter-finals of the competition.[57] On 6 July, Martínez scored the opening goal in a 1–1 draw in the semi-finals againstColombia; he later netted his spot kick in Argentina's eventual 3–2 penalty shoot-out victory to progress to the final.[58][59]
Martínez was included in the final 26-man squad for the2022 FIFA World Cup by Lionel Scaloni. Although he was struggling with an ankle injury, he started the initial two games of the tournament, having a goal disallowed for offside in Argentina's opening 2–1 defeat toSaudi Arabia, before being dropped from the starting lineup forJulián Álvarez, and would come off the bench for the remainder of the tournament, going scoreless throughout the competition.[61][62][63] On 9 December 2022, during thequarter-final, Martínez scored the winning penalty in Argentina's 4–3 shoot-out victory against theNetherlands to send his side into the semi-finals.[64] On 18 December, during thefinal, he replaced Álvarez in extra-time as Argentina defeatedFrance, 4–2, in the penalty shoot-out after the match ended 3–3 in extra-time to win the World Cup.[65]
At the2024 Copa América, Martínez scored Argentina's second goal in the team's opening 2–0 win overCanada.[66] He followed this up with the only goal of the match in a win againstChile, which allowed Argentina to advance to the knock-out stages.[67] In Argentina's final group match againstPeru, he scored both goals in a 2–0 win.[68] In thefinal againstColombia, Martínez scored the only goal in the 112th minute of the game during extra time, putting Argentina up 1–0, and eventually winning them the tournament. With his 5 goals in the tournament, he was awarded the Golden Boot as the competition's top goalscorer.[69]
Martínez initially played as adefender in his youth and later switched to aforward, citingRadamel Falcao as one of his influences.[70] A quick and agile player, he is known for hisdribbling skills, his prolific goalscoring, his positioning in the box, and his physical strength and aerial prowess despite not being particularly tall;[71][72][73] however, he has been criticised by pundits for his lack of accuracy when takingpenalties.[74] He also possesses good link-up play and defensive work-rate, and is capable ofassisting goals in addition to scoring goals himself;[73][75][76] because of this, he can also play as asecond striker, aside from his usual role as a striker.[77][78][79]
Due to his leadership and winning mentality, he has been nicknamedEl Toro ("The Bull," in Spanish).[80][81] In 2020, Spencer Rance of90min.com regarded Martínez as one of the most promising young players,[82] while managerMauricio Pochettino regarded him as one of the best strikers of his generation.[83] Former Argentina and Inter striker Hernán Crespo likened Martínez to compatriot Sergio Agüero in 2020.[84]
Since 2016, Martínez has been in a relationship with Agustina Gandolfo, an Argentine entrepreneur and fitness trainer.[85] On 27 May 2023, they got married inVilla d'Este onLake Como, Italy.[86]