Rosti's mother was enamoured with Egypt to the point that when it was time for the diplomat father to terminate his political assignment (in Cairo) and return to his country, she refused to travel with him and decided to remain in Egypt with her son.

[2] As a young man, Rosti travelled to Austria seeking recognition by his father, but to no avail.

Rosti met and befriended two visiting Egyptian film-makers, Mohammed Karim and Sirag Mounir, who encouraged him to return to Egypt to work in cinema, given his fluency in Egyptian Arabic and after he expressed his desire to do so.

Rosti returned to Egypt and enrolled as a student in the "Acting Institute" of Cairo, and accepted his first role as director of the first wholly Egyptian feature film, "Layla" from producer Aziza Amir in 1927.

He was renowned for portraying evil characters with a satirical inclination, and he became an icon of the Egyptian film industry.