Justin Bieber Surprises Deserving Fans in 'Knock Knock Live' Preview: Watch

Greg Gayne/FOX
Justin Bieber on Knock Knock Live airing Tuesday, July 28, 2015.

On the next episode of Fox reality show Knock Knock Live, Justin Bieber gets in on the fun (courtesy of his pal Ryan Seacrest, who is one of the hosts) when he surprises a very special family in church.

Billboard Hot 100 Music Festival

According to an episode description, the 21-year-old also surprises a girl at her quinceañera, which was surely an event to remember.

Check out a preview for the episode below. Knock Knock Live with Bieber airs on Fox tonight at 9 pm ET. 

Bieber is lined up for a very special performance at the Billboard Hot 100 Music Festival on Aug. 22-23 in Jones Beach, New York.