The venue, which features 30 meeting rooms holding up to 248 theatre style, held the event to launch a £100,000 refurbishment of its Orangery conservatory event space.
Since its launch the venue has hosted 2,500 events including conferences, meetings, dinner dances, summer and Christmas parties.
Corporate bookings have come from Balfour Beatty, Kingsley Napley, CH Communications and Hardwicke.
No 11 Cavendish commercial director Jonathan Morris said: "We launched the brand at a very difficult economic time and are delighted with the results we have achieved within a year.
"I was tasked with launching The King’s Fund’s newly refurbished event spaces and creating and launching a separate brand identity, No.11 Cavendish Square to tap into the corporate and commercial events industry as The King’s Fund is well established in the healthcare sector."
No 11 Cavendish Square last year hired Scott Ashby as general manager of catering and events.