He made his stage debut in Amsterdam in 1903, and over the next few years built a reputation to the point where he was invited to perform in Paris, eventually co-starring in several roles with Sarah Bernhardt, with whom he was involved romantically.

In 1910, Tellegen and Bernhardt travelled to the United States, where The New York Times first published, and then retracted, the announcement of their impending marriage.

Back in France, in 1912 they made their second film together, Les Amours de la reine Élisabeth (Queen Elizabeth), and the following year, Adrienne Lecouvreur.

In the summer of 1913, Tellegen went to London where he produced and starred in a play based on Oscar Wilde's novel The Picture of Dorian Gray.

Invited back to the United States, Tellegen worked in theatre and made his first American film in 1915, titled The Explorer, followed by The Unknown, both with Dorothy Davenport as his co-star.

Considered one of the best-looking actors on screen, he followed up with three straight films starring alongside Geraldine Farrar.