Stewart was born in Edinburgh, and is the son of the late famous Scottish entertainer Andy Stewart. Ewan's mother Sheila is still alive and lives in Arbroath, Scotland.

Stewart was educated at Edinburgh's Merchiston Castle School from 1966 - 1974. He left Scotland to move to London in 1975 and started working in theatres as well as studying drama.

Ewan Stewart's first TV appearance was in an advertisement for Scottish "Bluebell" matches. His first major TV appearance was in 1979 in the TV remake of All Quiet on the Western Front, with Richard Thomas, and Ernest Borgnine.

Stewart is married and lives in London with his wife, English actress Clare Byam-Shaw, and his two children, Thomas and Eleanor.

In 2005, Stewart was one of many European actors considered for the vacant role of James Bond for the 007 series.