Born in Vlădești, Argeș County, he graduated high school in Câmpulung in 1967 and Bucharest's Caragiale Academy of Theatrical Arts and Cinematography in 1971. He made his theatrical debut a year before graduating, at the Bulandra Theater, in Truman Capote's The Grass Harp. His screen debut came in Dan Pița's Nunta de piatră (1972); he would later appear in the same director's Filip cel Bun (1975). Other directors with whom he has worked include Alexandru Tatos (Mere roșii, 1975; Secvențe, 1982; and Secretul armei secrete, 1988), Virgil Calotescu (Buletin de București, 1982; and Căsătorie cu repetiție, 1985), Nae Caranfil (Asfalt Tango, 1996; and Filantropica, 2002) and Cătălin Mitulescu (The Way I Spent the End of the World, 2006). In all, he has appeared in more than sixty films. Diaconu worked with Lucian Pintilie both in film (the 1981 De ce trag clopotele, Mitică?) and in theater: Gogol's The Government Inspector at Bulandra, and Shakespeare's As You Like It at the Nottara Theater. Liviu Ciulei hired him at Bulandra in 1972, and he remained there for a decade, before moving on to Nottara. At Bulandra, he appeared in Twelfth Night and The Tempest, both under Ciulei's direction; and in Marin Sorescu's Răceala, directed by Dan Micu. At Nottara, he appeared in Alexander Ostrovsky's The Forest; Ultimul bal, after Liviu Rebreanu's Forest of the Hanged; and Mihai Ispirescu's Într-o dimineață. He became the director of Nottara Theater in 2004, working as such until his resignation in 2011.

Weet wanneer de volgende film van Mircea Diaconu uitkomt
Volg één keer, wij laten het weten zodra hij in de bioscoop draait.
Hij was een gevierde Roemeense film- en podiumacteur die afstudeerde aan de Caragiale Academie in Boekarest en decennia vormgaf aan het binnenlandse theater en de film.
Hij wordt algemeen erkend voor zijn optredens in Philanthropy, Asphalt Tango en Bucharest Identity Card.
Hij bracht een decennium door met optreden in het Bulandra Theater en diende later als directeur van het Nottara Theater. Volledig schema op Mood.