The two actors will play the previously revealed characters Taylor, a hot club promoter who can spot great talent like Adrianna (Jessica Lowndes), and Alec, a charming tech guy who is Max's (Josh Zuckerman) business partner.
Brown will portray Taylor, while Byers will star as Alec, reports Entertainment Weekly.
Brown previously appeared as Luke McDonald in True Blood's second season.
Meanwhile, Byers is a relative newcomer, who has starred in the soap opera All My Children.
90210 will return on Monday, October 8 on CW.
Watch a clip of 90210 below: