He began studying acting at the age of 5 in the theater company Guthrie Theater. His first role was when he played Tiny tim in the annual play of said theater, called “A Christmas Carol”.
He graduated from the Academy of Holy Angels’ High School in Richfield, Minnesota.
He has participated in several Broadway musicals such as “Tartuffe” Y “Noises Off“, And in others like”Boy“,”The Hologram Theory“,”Fool” Y “Voices of Peace and Dissent”.
On the big screen he was seen in movies like “Garment” Y “The Last Request”.
On television he participated as a guest actor in several series such as “CSI: Crime Scene Investigation“,”Sesame Street“,”Law & Order” Y “Frasier”.
Undoubtedly, his most important role so far has been that of George O’Malley in the renowned series “Grey’s Anathomy”.
It is worth mentioning that in October 2006, Knight revealed that he is homosexual in a statement he made to the magazine People, in which he said: “I suppose there have been some issues regarding my sexuality, and I would like to quell unnecessary rumors arising from it. Although I prefer to keep my personal life private, I hope that the fact that I am gay is not the most interesting part of me“.
The topic aired when one day when Theodore came to shoot a scene, so his co-star, Isaiah Washington (Dr Burke) did not want to wait for him to roll, to which Patrick Dempsey (Dr. Shepherd) objected, and this fact generated a discussion that ended in insults dedicated to Knight about their sexuality.
It should be noted that her best friend is her co-star in “Grey’s Anathomy”, Katherine Heigl, and he was even her best man at the wedding.
He currently lives in Los Feliz, California.