Blackburn was born in Burbank, California. He has three brothers and a sister. He is of English, Welsh, Czech, and Swedish descent.
Blackburn has a 4 inch long scar on his left shoulder. This was caused due to the removal of a benign bone tumor at the age of 10.
Blackburn began performing in 2004 and appeared on the series Unfabulous on Nickelodeon. In the following year he was a teacher in the short film The Doers of Coming Deeds. In 2008, he made a cameo in the film Next of Kin. In 2007, Blackburn appeared in Cold Case and Rockville CA, a webseries launched by Josh Schwartz. In 2010, he appeared on Days of Our Lives, Gigantic, and was also in the independent film Peach Plum Pear.
In October 2010, Blackburn was cast in a recurring role as Caleb Rivers in the television series Pretty Little Liars. He was upgraded to series regular for the third season starting in the summer of 2012. In March 2011, he joined the cast of the NBC comedy pilot Brave New World, which was not picked up to series.
Blackburn also starred as Pete in the six-episode web series Wendy, a project developed by Alloy Entertainment and Macy's that was based on Peter Pan which premiered on September 15, 2011. In 2012, he starred in drama Hiding alongside Ana Villafañe, Jeremy Sumpter, Dean Armstrong and Dan Payne.
For his role in Alloy Entertainment web series Wendy, Blackburn recorded a song that was released on August 15, 2011. He recorded another song for the ABC Family television show, The Secret Life of the American Teenager. He recorded "Find a Way" in 2012 and the song played while he was starring as Caleb Rivers in Pretty Little Liars.
In May 2013, it was announced that Blackburn would star in the 2013 Pretty Little Liars' spin-off Ravenswood.
In March 2018, Blackburn joined the cast of The CW series Roswell, New Mexico.
Was nominated for 4 Teen Choice Awards.