Justin Martinez Bio
Justin Martinez (born July 30, 2001) is a Dominican professional baseball pitcher for the Arizona Diamondbacks of Major League Baseball (MLB). He made his MLB debut in 2023 after signing with the Diamondbacks as an international free agent in 2018. Over the course of his early career, Martinez has shown promise despite facing challenges with injuries, and he recently secured a five-year contract extension with the team.
Early Life and Background
Justin Martinez was born on July 30, 2001, in the Dominican Republic, a country with a long tradition of producing Major League Baseball talent. Growing up in a baseball-rich environment, he developed an early passion for the sport and worked toward a career as a professional pitcher. Limited public information is available about his family background or formal education, as is common for many young Dominican players who begin their professional paths as teenagers.
Martinez committed to a professional baseball career at a young age, choosing to pursue opportunities in the United States through the international free agent system. His decision to sign with a Major League organization at 16 years old reflected both his talent on the mound and the strength of the Dominican Republic’s player development pipeline. That early commitment set the foundation for his progression through the minor leagues and ultimately to the big leagues.
Path to Baseball
Martinez signed with the Arizona Diamondbacks as an international free agent on March 5, 2018, beginning his professional career in the Dominican Summer League. He spent his first season refining his pitching skills in the DSL, where he quickly showed the kind of arm talent that Diamondbacks scouts had identified during the signing process. That debut year established him as a prospect worth following within the organization’s developmental system.
In 2019, Martinez split the season between the DSL Diamondbacks, the rookie-level Arizona League Diamondbacks, and the rookie-level Missoula Osprey. Across 18 games, including 10 starts, he posted a 2.89 ERA with 78 strikeouts in 56 innings, demonstrating both his strikeout ability and his capacity to handle multiple affiliates in a single year. His progress, however, was interrupted in 2020, when the minor league season was canceled due to the COVID-19 pandemic, preventing him from gaining valuable innings during that developmental period.
Justin Martinez Career
Early Career (2018–2021)
Martinez returned to action in 2021, beginning the season with the Single-A Visalia Rawhide. Unfortunately, his campaign was cut short after only seven starts, as he underwent Tommy John surgery. The procedure represented a major setback for the young pitcher, but it also became a turning point in his development, allowing him to rebuild his mechanics and add strength to his arm during an extended rehabilitation period.
He came back in 2022 and pitched across four affiliates, including the rookie-level Arizona Complex League Diamondbacks, High-A Hillsboro Hops, Double-A Amarillo Sod Poodles, and Triple-A Reno Aces. In 20 games, he recorded a 3.32 ERA with 62 strikeouts in 38 innings. After the regular season, Martinez joined the Arizona Fall League and earned a spot in the league’s all-star game in November, a strong signal that he was back on a major-league trajectory. On November 15, 2022, the Diamondbacks added him to the 40-man roster to protect him from the Rule 5 draft.
MLB Debut and Rookie Season (2023)
Martinez was optioned to the Triple-A Reno Aces to open the 2023 season, where he posted a 4.18 ERA with 38 strikeouts and five saves in 28 innings across 25 games. His performance earned him a first promotion to the majors on June 27, 2023, but he went unused in the bullpen and was sent back to Reno two days later, technically making him a phantom ballplayer. He returned to the big leagues on July 7, making his official MLB debut the same day against the Pittsburgh Pirates, allowing two runs in one inning of relief.
Across 10 appearances during his rookie campaign, Martinez struggled to a 12.60 ERA with 14 strikeouts in 10 innings. Despite the difficult numbers, the experience of pitching at the major league level provided valuable lessons and gave the Diamondbacks a clearer picture of the work he needed to do in the offseason.
2024 Breakthrough
Martinez was again optioned to Triple-A Reno to begin 2024, but he rejoined the Diamondbacks and established himself as a reliable late-inning reliever. He made 64 appearances, posting a 5-6 record and a strong 2.48 ERA with 91 strikeouts and eight saves in 72 2/3 innings pitched. That workload represented a major step forward in his career, marking his first full major league season and showcasing the improvements he had made in command and consistency on the mound.
Arizona Diamondbacks Era (2025–Present)
On March 21, 2025, Martinez and the Diamondbacks agreed to a five-year, $18 million contract extension, signaling the organization’s long-term commitment to him. The deal reflected both his 2024 performance and his potential as a high-leverage reliever going forward. Early in the 2025 season, he appeared in 17 games and recorded a 1-2 record with a 4.11 ERA, 22 strikeouts, and five saves in 15 1/3 innings.
On June 10, 2025, Martinez was placed on the injured list due to a right UCL sprain. Three days later, it was announced that he would undergo Tommy John surgery, ending his 2025 season. The injury marked a significant obstacle, but the contract extension suggested that the Diamondbacks remained confident in his long-term outlook.
Notable Events and Milestones
Martinez’s major league debut on July 7, 2023, against the Pittsburgh Pirates stands as a defining moment in his career. His first full major league season in 2024, in which he posted a 2.48 ERA across 64 appearances, marked the most significant milestone of his career to date. The five-year, $18 million contract extension signed in March 2025 further cemented his place within the Diamondbacks organization and highlighted his value as a late-inning arm.
Justin Martinez Family
Family Background and Personal Life
Public information about Justin Martinez’s family background is limited. He is from the Dominican Republic, a country widely recognized for producing Major League Baseball talent, and he began his professional career as a teenager after signing with the Arizona Diamondbacks in 2018. Further details about his parents, education, marital status, or residence are not publicly documented in available sources.
2025 Season Performance
Justin Martinez’s 2025 season was shaped by both opportunity and adversity. After signing a five-year, $18 million contract extension on March 21, 2025, he opened the year in a high-leverage role for the Diamondbacks. Across 17 appearances, he recorded a 1-2 record with a 4.11 ERA, 22 strikeouts, and five saves in 15 1/3 innings pitched, contributing to the Arizona bullpen during the early months of the season.
His season, however, came to an abrupt halt on June 10, when he was placed on the injured list due to a right UCL sprain. Three days later, the team announced that he would undergo Tommy John surgery, ending his 2025 campaign. Despite the injury setback, his contract extension runs through 2030, leaving room for a full recovery and a return to the major league mound in subsequent seasons.