Jensen was born in Dallas, Texas. His father Alan Ackles was an actor in the Dallas area, so he was exposed to the entertainment industry at a young age. When he was a sophomore in high school, a friend asked him to come along to a local acting seminar. After getting an agent, he landed his first audition--a guest spot on "Sweet Valley High." After that he moved to Los Angeles on his agent's suggestion. He booked "Days of Our Lives" soon after his move. He had successes in guesting on WB hits "Dawson's Creek" and "Smallville" as Jason Teague. He currently stars with Jared Padalecki on the WB hit Supernatural.