The one-day-only event, Redlight, takes place on Saturday, July 26 from 2pm to 2am.
Organisers promise a packed 12 hours of music, food and drinks, with tracks spanning genres and decades.
Festival-style food will be available on site, and the venue’s usual weekend deals on cocktails and mixers will be running throughout the day.
The pub’s newly revamped garden huts and indoor booths can also be booked for the event.
A spokesperson said: “We really want to make this an event for everyone (18+!) with two stages to choose from, festival-style food available and our usual fantastic weekend deals on cocktails and mixers.
“We’re so excited to bring the festival scene to Blackfen for a day, and so are our customers, if the speed at which tickets are selling is anything to go by.”
Headlining the day is UK DJ and producer Redlight, known for tracks like 9TS (90s Baby), Get Out of My Head, and Lost in Your Love. Support comes from Collective Audience, Liberate Ldn and DJ Dan Scott.
Tickets start from £5 for early entry, with general release priced at £10.
Outdoor huts and indoor VIP booths for groups of up to eight are available for £75.
All tickets are available through The George Staples website, and the event is strictly 18+ with ID required on the door.
