At the age of 18, Mastorakis as a young reporter with the Greek newspaper Ethnikos Kirikas scored his first international scoop, an exclusive interview with the exiled Princess Soraya.
He produced local versions of many international formats (Candid Camera, To Tell The Truth) and worked for both YENED and ERT, the country's national TV network.
In addition to his shows he produced and directed Alati kai Piperi (Salt and Pepper), hosted by noted Greek columnist Freddy Germanos.
He wrote, produced and directed dramatic series and variety shows as well as the short-lived breakthrough sci-fi episodic Invasion From Another Planet, the first on Greek TV to be shot on film.
After writing a long piece about Mikis Theodorakis’ concert in London, for the weekly magazine Epikera, he was arrested and detained at the ESA (Military Police) headquarters for a day.
[citation needed] Unable to work in public television after the junta, Mastorakis turned to commercials and features and eventually left the country in 1975 to pursue his career as a B-movie-maker overseas.
He had already made two low budget movies, one of which later became a cult classic (Island of Death) and while living in London he wrote the screenplay for The Greek Tycoon (1978), a roman à clef based on his encounters with Aristotle Onassis.
He has since written, produced and directed 17 features, mainly low budget but with awards attached (Blind Date, Nightmare at Noon, Grandmother's House) and distribution by major studios and mainstream TV networks.
He then later started production company/distributor Omega Entertainment, in which, by November 1987, had sold off all rights to the 9 major films in 14 major territories and most of the small ones to distributor RCA/Columbia Pictures International Video, excluding North American rights to pics such as Glitch, Nightmare at Noon, Bloodstone and Under the Gun, and the titles he was set to produce and occasionally direct cost $5 million and claimed that his titles would be like hot cakes.