The Crown Club is located in the 18th Century old Crown offices and overlooks the swimming pools and gardens of the five-star Guernsey hotel.
Two outside terraces with outdoor heaters and fountain lighting complement the main conservatory area - one is designed as a Cuban cigar terrace, the other features a space for outside dining.
Both terraces will be accessible from the bar itself or from elsewhere, something Andrew Chantrell, general manager of The Old Government House Hotel & Spa, said he hoped would help make the new bar a destination venue.
"The Crown Club is going to be truly unique for Guernsey and we are very excited about being able to offer such a fantastic venue to discerning business and leisure guests," he said.
"It’s a beautiful building which has been sensitively restored and is a fabulous addition to The OGH. I have no doubt it will quickly establish itself in the affections of Guernsey residents and visitors alike," he added.
The Crown Club features a drinks menu with a selection of premium whiskeys and British gins as well as vodkas, cognacs, beers and wines including blends from the hotel operator's own estate in South Africa.
An informal light dining menu with a focus on sandwiches featuring local ingredients - such as Guernsey lobster and Donald Russell beef - will be on offer.
The bar, which also overlooks the island's famous Sunken Gardens, is decorated in a regency-inspired design with upholstered walls and antique features in keeping with the historical listed building in which it is located.
However, the bar features a number of five-star features including Mirror TVs and free Wi-Fi throughout.
A number of private boardrooms will be available to guest as well as a glass-walled wine and whisky tasting room.
"For a relatively small space, The Crown Club offers a number of options, from our outdoor terraces and the light airy conservatory to the intimacy of the plush bar, meeting rooms and the wine tasting room," Chantrell said.
Red Carnation Hotels operates a collection of 14 four and five-star family-run boutique hotels.