Haynes began his career as a model at the age of fifteen in New York City, New York. Haynes first began his success after appearing in a Bruce Weber photoshoot for Abercrombie & Fitch. He also appeared in a photo shoot for XY Magazine in 2006. Afterward, Haynes began modeling in campaigns for Kira Plastinina, J. C. Penney, and Ralph Lauren. In 2008, Haynes continued modeling in campaigns such as Verizon and also appeared in numerous magazine editorials such as Teen Vogue and Arena.
He made an uncredited appearance as a young man in a cafe in the 2007 blockbuster Transformers. He also made a guest appearance on CSI: Miami, where he portrayed Brandon Fox, a young man who fails to commit suicide after being in a massive debt. He made a cameo appearance as a model in two episodes of The Hills. In addition to guest roles, Haynes also acted in My Chemical Romance's music video for their single, "I Don't Love You", directed by Marc Webb. In the second half of 2007, Haynes auditioned for the role of Edward Cullen in the film version of Stephenie Meyer's young adult novel, Twilight. Robert Pattinson was cast instead.
In 2008, he guest appeared as Alexander on the television series, Privileged, and also appeared as Ares Kostopolous on the television series, Pushing Daisies. He won the role of Scott Holland in the Hallmark Channel film, Always and Forever. Filming began in December 2008, and the film was released to television on October 24, 2009. He unsuccessfully auditioned for the role of Royce Du Lac in the Nickelodeon film, Spectacular!.
It was announced in 2009 that Haynes had won the role of Shane in the Showtime series Look, based on the 2007 film of the same name. “I play a 17-year-old asshole. The show is very racy with lots of nudity, sex, drugs and real life experiences that will shock audiences," Haynes said in an interview. Filming began in the summer of 2009 and it is expected to premiere in 2010. He also landed the role of Jackson in the MTV series, Teen Wolf, based on the 1985 film of the same name. In March 2010, filming began for the ABC television series, The Gates, in which Haynes portrays Brett Crezski, a jock who begins to turn into a werewolf. The series premiered on June 20, 2010.
- Colton is 5'11.
- Won “Gatorade Player of the Year” Award his junior year in tennis.
- Worked as the Red Robin bird mascot at a restaurant in high school
- Can move both of his eyebrows up and down and wiggle his ears.
- Has a wall in his house that is called “The Great Wall of Positivity” where he writes all of his positive thoughts.
- Ranch dressing is his guilty pleasure.