Justin Bieber, Ariana Grande to Appear on Ryan Seacrest’s ‘Knock Knock Live’

Rob Gronkowski, Rita Ora, Martha Stewart, Robin Thicke and Bubba Watson also to guest on Fox’s new live unscripted show

Justin Bieber and Ariana Grande are among the new stars scheduled to appear on Fox’s upcoming unscripted series “Knock Knock Live,” hosted by Ryan Seacrest.

Fox announced that Bieber, Grande, Rob Gronkowski, Rita Ora, Martha Stewart,  Robin Thicke and Bubba Watson will join a lineup of celebrity guests that previously included David Beckham, Luke Bryan,  Common, Florida Georgia Line, Mike Holmes, Lea Michele and Meghan Trainor.

“Knock Knock Live” is scheduled to premiere July 21 at 9 p.m. The show will feature Seacrest and co-hosts surprising people at home with games, cash prizes and chances to interact with celebrities. It is produced by Simon Fuller’s XIX Entertainment and Dick Clark Productions.

Seacrest and an unnamed guest will tease the show Tuesday night with an appearance during Fox’s broadcast of the Major League Baseball All-Star Game, in which they will surprise a fan at home.