Efi Stamouli was born in Thessaloniki. She graduated from the Drama School of the National Theatre of Greece (1978) and the Department of French Literature of the Aristotle University of Thessaloniki (1981). For a year (1978) she worked at the National Theatre of Greece and immediately afterwards, in 1979, she was a founding member of the Experimental Stage of "Techni", where she has remained with short breaks to this day. She has performed many roles in the classical and contemporary repertoire, having taken part in over 100 plays. Among them: Shakespeare, A Midsummer Night's Dream (Titania), Loulas Anagnostaki, The City (Elisabeth), Beckett, Waiting for Godot (Pozzo), Chekhov, Uncle Vanyas (Sonia), Ilias Kapetanakis, The Wenge (Froso), Marivaux, The Quarrel (Eglet), Goldoni, The Summer Trilogy (Giacinta), Ibsen, Enda Gambler (Eda), Shakespeare, A Midsummer Night's Dream (Pook), Brecht, The Chalk Circle (Grusa), Eric Rohmer, Trio in E flat (Adele), Catherine Anne, Tita-Lou (Tita), Euripides, Ion (Creoussa), T. Wertenbaker, For the Good of the Country (Liz Morden), Shakespeare, Twelfth Night (Viola), Iakovou Kambanelli, In Ibsen's Country (Elena Alving), Yannis Ritsou, The Dead House & The Moonlight Sonata, Chekhov, The Three Sisters (Masha), Brian Friel, Dancing in Lunasha (Kate), Brecht, Mother Courage (Anna Fierling), D. Kehaidi-El. Caviar, With Power from Kifisia (Fotini), Ingmar Bergman, After the Rehearsal (Raquel), Michael Frayn, Save It (Mrs. Clackett), Aristophanes, Churchgoers (Gria), Chekhov, The Seagull (Arkantina), Frank McGuinness, Working Girls (Ellen), Loulas Anagnostaki, Victory (Vasso), Ibsen, Vampires (Mrs. Alving), Akis Dimou, Tonight We Eat at Jocasta's (Jocasta), Joel Pommera, The Merchants (Narrator), Martin Cribb, In the Countryside (Corinne), Fento, The Smart Bird (Lucien), S. Serefa, The Road Will Take You, Frank McGuinness, Greta Garbo Came to Our Town (Greta Garbo), Carol Fresset, The Secret Room (Catherine), Chekhov, The Cherry Orchard (Lyubov Andreyevna), Dürrenmatt, The Old Lady's Visit (Claire Zahanasian), Martin McDonagh, The Beauty Queen (Magg), Beckett, The Endgame (Clove), Papadiamantis, Murder (Frangogiannou) etc.

In 2002, she collaborated with the NTNG, playing the leading role in George Skampardonis' play Gernao successfully, while from 2015 onwards she had the following collaborations with the same organization: Sofia Adamidou, My Name Is Sotiria (Sotiria Bellou), Dimitrios Koromilas, The Shepherdess' Lover (Yianenna), Emily Bronte, Wuthering Heights (Nelly), Ibsen, Pillars of Society (Betty Bernick).

She has collaborated with the directors: Nikos Hourmouziadis, Colin Harris, Nikos Charalambous, Nikos Armao, Nikos Politis, Takis Kalfopoulos, Eleni Karpeta, Ersi Vasilikioti, Pepi Oikonomopoulou, Nikiforos Papandreou, Glykeria Kalaitzi, Petros Zivanos, Andreas Voutsinas, Nick Filippou, Nikos Hatzipapas, Sotiris Hatzakis, Yannis Moschos, Yannis Leontari, Christina Hatzivassiliou, Stamatis Fasoulis, Yannis Kalavrianos. She has translated plays (Yukio Mishima, Charlotte Kitley, Connor MacPherson, Lolé Bellon). She has taught Acting at the Drama School of the National Theatre of Greece. Since 1997, she has taught Acting at the Theater Department of the Aristotle University of Thessaloniki.