Justin Deeley and Megalyn Echikunwoke will both appear in multiple episodes of the teen drama's fourth season, according to TV Line.
Deeley will play Austin, the son of a country music star and a new love interest for Naomi (AnnaLynne McCord).
He previously starred in 2009 film comedy Couples Retreat and also played a stripper in 90210's third season finale.
Former CSI: Miami star Echikunwoke will appear as Holly, a popular but conceited sorority girl who clashes with Naomi at college.
The actress recently appeared in an episode of Law & Order: Special Victims Unit and will also feature in Don Cheadle's new Showtime series House of Lies.
It was recently announced that Privileged actress Kristina Apgar will star in 90210's fourth season as Jane, a young widow who has feelings for Liam (Matt Lanter).
90210 will return to The CW on September 13.
> Trevor Donovan to leave 90210
Watch a clip from the 90210 third season finale below: