Daniel "Dani" Martínez Moreno was born on 5 May 2004. He came through Atlético Madrid's academy structures and was promoted to the B side, Atlético Madrileño, on 1 July 2023. He renewed his contract through 30 June 2027 in July 2024 and established himself as a regular starter at the reserve level over the 2024–25 and 2025–26 campaigns.
Martínez made his professional and La Liga debut for the senior team on 11 April 2026, starting in a 2–1 away loss to Sevilla — a high-profile bow that crowned a season in which he had repeatedly trained with the senior squad as right-side defensive cover.
A 1.86 m right-footed centre-back who can also fill in at right-back, Martínez is praised at academy level for his composure on the ball, recovery pace, and physical presence. He is one of the most carefully tracked defensive prospects in La Cantera's current cycle, and his senior debut positions him as a candidate for further first-team minutes through 2026–27.