Annabel's is a private members' club at 46 Berkeley Square in Mayfair, London.

It was opened at 44 Berkeley Square in 1963 by Mark Birley and named for his wife Lady Annabel Vane-Tempest-Stewart. It was founded in the basement of the Clermont Club, a private gambling club established by John Aspinall. Annabel's was one of the first nightclubs in London and was especially popular with the British aristocracy and the international jet-set in the 1960s and 1970s. It was revived by Birley's son and daughter in the 2000s and was sold by Birley with his other members' clubs to Richard Caring in 2007. Annabel's closed at No. 44 Berkeley Square in 2018 and was reopened later that year at No. 46, occupying the entirety of the Georgian townhouse.

In 1962 the Clermont Club, a private gambling club catering to London's high society, was established at 44 Berkeley Square, a townhouse in the Mayfair district of London, in 1962 by John Aspinall. The house was built between 1742 and 1744 by William Kent for Lady Isabella Finch. The Clermont Club was one of the first private gambling clubs in London following the passing of the Betting and Gaming Act 1960.

Aspinall suggested to his friend Mark Birley that he start a piano bar in the extensive vaults and basement of No. 44. Birley himself had intended to start a club after being inspired by the piano bar of the Carlyle Hotel in New York. 6,000 tonnes of London Clay were removed from the basement and garden at the rear of the house to create the principal rooms of the club. The dance floor of the club was the floor from the old kitchen of No. 44. Annabel's was linked to the Clermont Club upstairs by an internal staircase, which was subsequently blocked off by Birley. Birley blocked off the staircase due to his disapproval of Arab gamblers coming down into Annabel's from the Clermont Club in various states of "dress and disorder which jarred with the tone of the nighclub" as recalled by Jonathan Aitken.

Birley named the club for his wife, Lady Annabel Vane-Tempest-Stewart. After almost two years of preparations, the club opened on 4 June 1963, Birley having borrowed £175,000 (equivalent to £4,628,654 in 2023) to establish the club. Lady Annabel herself said that she was not fond of having the club named after her when it first opened but subsequently looks back " ... on [Birley's] decision with pride and consider it the most tremendous compliment he could ever have paid me. Having a nightclub named after you is much better than being immortalised as a rose, which, unlike Annabel's, does not necessarily survive very long". The club became colloquially known by rich debutants as "the 'Bel's".

Annabel's was launched by an opening night party on 4 June 1963. Annabel's had a seating capacity of only 225 people and became quickly overcrowded with Mark and Annabel Birley's friends and their relations. Lady Annabel later wrote that for " ... at least an hour it was bedlam. I had visions of oxygen masks and people being trampled to death" but " ... by the early hours of the morning the crowd miraculously began to melt away, and the rest of the night was magical". Annabel also accidentally insulted the American ambassador to the United Kingdom, David Bruce, and the actor Peter O'Toole by telling them there was no room for them. Lady Annabel recalled that the guests on opening night " ... sounded like a roll call for the pillars of society". By 5am only Mark and Annabel Birley and James Goldsmith and his girlfriend Sally Crichton Stuart remained on the dancefloor.

Rival high society clubs to Annabel's in the 1960s included Siegi's and Les Ambassadeurs.

Unaccompanied journalists were not allowed in Annabel's except for the gossip columnist Nigel Dempster.