Antonio Romero Cienfuegos has collaborated with different orchestras such as the Orquesta Sinfónica de Galicia, the Real Filharmonía de Galicia, the Orquesta Sinfónica de Radio Televisión Española, the Orquesta Sinfónica de Valencia, the Orquesta Sinfónica de Madrid, the Orquesta Sinfónica do Principado de Asturias, the Orquesta Sinfónica de Castilla y León or the Orquesta de la Comunidad de Madrid. Likewise, he has collaborated in other orchestral and pedagogical projects such as the Orquesta GAOS, the European Youth Wind Orchestra, the Academia Contemporánea Via Stellae, the Camerata OSG, the National Youth Orchestra of the Netherlands (NJO) Summer Academy or the Festival Turina and has played as a soloist. the double bass concerto by J. Françaix, the Carmen Fantasy by Frank Proto and the Concertino op. 45 no. 11 by L. E. Larsson.

As a composer, he has premiered the work Paseando por New York for double bass quintet; Fendas, for choir, piano and recital, written for the Ludus Tonalis chamber choir; and, more recently, Little… tango? for double bass orchestra. He has also premiered several works: Number 4 by Antonio Portela Rodríguez; the Sonata for double bass and piano and 4 Pieces for vibraphone and double bass by the composer, also Galician, Federico Mosquera Martínez; Bourrée for solo double bass by Armand Russell; Suspiros, Serenata, Duo for double bass and cello and Duo No. 1 for violin and double bass by Josep Cervera i Bret; and Suite for double bass and piano by the composer Francisco García Álvarez and Dialogue and Once in the evening by Ilona Dyagileva.

He has received several awards throughout his career: 2nd prize in the XI Concurso Diputación de Toledo for string instruments (2008); 3rd Prize for Excellence from the Fundación Paideia (2012); 3rd Prize at the International Music Competition London Grand Prize Virtuoso 2016; and Honorable Mention in Concurso Internacional de Jóvenes Solistas de la Costa Atlántica (2016). In 2021 he won the 1st Prize at the International Moscow Music Competition, in the Ensemble category, with the group Tempo Catro and in 2023 he received a double prize at the World Classical Music Awards: the gold medal in the current music category and the Grand Prize among all categories.