In July 2012, Johnson signed a clothing deal with Asics America and he is represented by Sam Duvall at Lagardere Unlimited.He currently trains at the USTA Player Development Center West in Carson, California.He missed just two because of junior tennis events and did not lose a set in team competition on his way to winning his second consecutive Golden West League title.
His only high school loss of 2006 was a three-set defeat in the semifinals of Ojai to eventual champion Jason Jung of West Torrance.
He then defended his title by beating current UCLA tennis player Alex Brigham.
He also has the distinction of being the only player to win the Triple Crown, singles and two doubles—twice. He was ranked the third-rated California senior tennis recruit (7th overall) in the country, according to Tennis
Lastly, he clinched the title for Southern California at the 2007 Junior Davis Cup.
At USC, Johnson majored in human performance, but left when he was three classes short of attaining his degree.