Oparei began his career working for various British theatre companies, like Theatre De Complicite, The Royal Shakespeare Company and The Royal National Theatre. Oparei's film debut was a small supporting role in Alien 3. After playing the lead role of American Playwright John Guare's Six Degrees of Separation, Oparei scored his next supporting film role, as "Le Chocolat", in the Baz Luhrmann film Moulin Rouge!. In 1993, he appeared in an episode of the popular British television series Minder as 'Winston', a worker for Arthur Daley
In 2015, Oparei joined the cast of the HBO epic fantasy series Game of Thrones in its fifth season, portraying the character Areo Hotah.
