Carlos Cosías won the first Manuel Ausensi Singing Competition in Barcelona and, in the same year, received the Plácido Domingo–Pepita Embil Prize for Best Zarzuela Singer at Operalia, as well as second prize at the Francesc Viñas International Competition at the Gran Teatre del Liceu, where he also earned awards for Best Donizetti Interpreter and Best Spanish Singer. In 2015, he was named Best Male Voice by the Spanish Lyric Association.
He has performed leading roles in works such as Don Pasquale, L’elisir d’amore, Anna Bolena, Lucia di Lammermoor, La sonnambula, Die Zauberflöte, Don Giovanni, La traviata, Rigoletto, Falstaff, La bohème, and Gianni Schicchi, as well as zarzuelas including Doña Francisquita, Marina, La tempestad, and El rey que rabió.
He has appeared at major venues including Maggio Musicale Fiorentino, Opéra de Nice, Teatro Nacional São Carlos in Lisbon, Teatro de la Zarzuela, Teatro Arriaga, and Teatro Campoamor. He is also active in concerts and recitals at venues such as the Palau de la Música Catalana and the Miguel Delibes Auditorium.
He has taken part in the Festival del Mil·lenni alongside José Carreras and Plácido Domingo, and has performed across Europe, the United States, and Asia.
He made his debut at the Gran Teatre del Liceu during the 1999/2000 season with Lucia di Lammermoor and has returned for La traviata (2001/02), Doña Francisquita (2009/10), Falstaff (2010/11), Carmen (2023/24) and Madama Butterfly (2024/25).