The new season of the hit reality competition series "Big Brother" includes new elements including the introduction of a mysterious masked visitor with a secret accomplice and an unknown houseguest to be revealed sometime during the season.

The “Big Brother” 27 live feeds won’t begin until Sunday, July 13, at 12:30 a.m. ET, which is three full days after the premiere. It’s likely that the feeds are being delayed to preserve the mystery houseguest’s identity, which suggests that we won’t know who they are until the July 13 episode of “Big Brother.”

Big Brother Season 27 is about to premiere on July 10, 2025, on CBS. Ahead of the reality show's premiere, the official cast list has been revealed. A total of 16 housemates will enter the house.

Big Brother viewers up North in Canada can watch Big Brother Season 27 simultaneous with their US cousins on Thursday, July 10 at 8pm ET/PT via the Global TV channel. Episodes will air weekly every Wednesday, Thursday, and Sunday.

Julie Chen Moonves returns to host Big Brother Season 27, which premieres with a 90-minute episode on Thursday, July 10 at 8 p.m. ET on CBS. A second 90-minute episode will follow on Sunday, July 13 at 8 p.m. ET. RELATED: ‘Survivor 50’ Cast Photos: All The Castaways Confirmed For CBS Competition