On 8 September 2017, Martínez extended his contract until 2022.[2] He scored his first senior goal nine days later, netting his team's first in a 2–2 draw at CD Lealtad.[3]
Martínez made his professional debut on 31 May 2019, replacing goalscorer Xisco in a 3–2 away success over Córdoba CF in the Segunda División, as his side was already promoted.[4] His La Liga debut occurred on 19 July of the following year, as he replaced fellow youth graduate Kike Barja late into a 2–2 home draw against RCD Mallorca.[5]
Martínez scored his first professional goal on 17 January 2021, netting the opener in a 2–0 away win over RCD Espanyol, for the season's Copa del Rey. His first goal in the main category occurred on 21 April, as he again netted the opener in a 3–1 success over Valencia CF also at the El Sadar Stadium.
On 1 September 2022, Martínez was loaned to Albacete Balompié in the second division, for one year.[6] The following 31 January, he moved to fellow league team SD Huesca also in a temporary deal.[7]
On 23 August 2023, Martínez returned to Huesca on loan for the 2023–24 season.[8]