Martin Tzonev has performed leading bass parts including Colline in La Bohème (Vienna, Volksoper), Don Magnifico in La Cenerentola (Regensburg and Bonn), Paolo Albiani in  Simone Boccanegra (Mannheim and Bonn), Litore, Console in L'Incoronazione di Poppea (Amsterdam, De Nederlandse opera), both Leporello (Lübeck and Bonn) and the title role in Don Giovanni (Telón del Teatro Segura and Lima), Don Basilio in Il Barbiere di Siviglia, Banco in Macbeth, Mephistophélès in Faust, Padre Guardiano in La Forza del destino, Four Villains in Les Contes d'Hoffmann, Gobriaz in Belsazar, and Zebul in Jephta (Bonn).

Martin Tzonev performed Colline in La Bohème, Figaro in Le Nozze di Figaro, Mephistophélès in Faust , Surin in The Queen of Spades, and Selim in Il turco in Italia, all in Bonn, where he is fixed engaged at present.

Highlights of past seasons include the title role in Don Giovanni (Gijon) and Eurito in Pizzetti's Fedra (Festival Radio France), Ramfis in Aida (Salle Pleyel, Paris and Montpellier), Mephistophélès in Faust (Montpellier), and Astolfo in Vivaldi's Orlando Furioso (Bonn).

Recent and upcoming engagements include Theaterdirektor, Bankier in Lulu (Salzburger Festspiele), Reimar in Tannhäuser, Zuniga in Carmen, Tchelio in Liebe zu drei Orangen, Leporello in Don Giovanni (Bonn), and Il Re in Aida (Stuttgart), Wotan in Die Walküre (Sofia), Le père de la famille in Berlioz' L'enfance du Christ (Het Gelders Orkest, the Netherlands), among others.