Born in Vigo, Galicia, Mariño played for Villarreal CF since the age of 14, having already represented four teams as a youth. He made his professional debut in the 2010–11 season, helping the reserves barely avoid relegation from the Segunda División while appearing in 38 games.[3]
Mariño was again first choice the following campaign, but as the main squad suffered relegation in La Liga the B's were forced to drop down to Segunda División B even though they had finished in a comfortable 12th position. After the departures of longtime incumbent Diego López and 41-year-old César Sánchez (the latter retired), he was promoted to the first team by manager Julio Velázquez – also his boss in the second side.
Valladolid and Levante
Mariño signed a five-year contract with Real Valladolid on 5 July 2013, with Villarreal retaining an option to buy him back for €300,000.[4] He made his debut in the top flight on 17 August, in a 1–2 home loss against Athletic Bilbao.[5]
On 8 August 2014, Mariño moved to Levante UD of the same league in a season-long loan.[6][7] On 31 August of the following year, he signed a permanent three-year deal with the club.[8]
On 18 January 2018, Mariño extended his contract until 2022.[12] Between 4 February and 1 April he was unbeaten during 764 minutes[13] and, at the end of the season, he was named Sporting's player of the year.[14]
In August 2019, another year was added to Mariño's contract.[15] He remained first-choice at El Molinón in the ensuing seasons, even after the re-acquisition of Cuéllar in 2021.[16] He suffered a right hamstring injury the following March and was replaced by the latter for ten games as the side successfully fought relegation,[17] returning on 29 May for the final match of the campaign in a 1–0 home defeat against UD Las Palmas.[18]
Almería
On 26 January 2023, Mariño returned to the top tier after agreeing to an 18-month contract with UD Almería.[19] He made his only appearance of the season on 4 March, as a half-time substitute for the injured Fernando and conceding both goals in a 2–0 home loss to Villarreal.[20]
Mariño spent the 2023–24 campaign as a third-choice behind Luís Maximiano and Fernando as they suffered relegation, and left the club in July 2024.[21]
Granada
On 10 September 2024, Mariño agreed to a one-year deal with Granada CF in the second division.[22]
^Domingo Carruébano, Estefanía (2 April 2018). "764 minutos para seguir soñando" [764 minutes to continue dreaming] (in Spanish). Vavel. Retrieved 28 June 2018.
^Fernández, Borja (21 May 2022). "Cuéllar busca completar la mejora" [Cuéllar seeks to complete upgrade] (in Spanish). Killer Asturias. Retrieved 6 September 2022.