The Lake District hotel beat off stiff competition from Dukes Hotel in St James, London, and properties in Malta and Thailand to scoop the prize on Thursday.
General manager Alasdair Elwick, recently-appointed head chef Ian Swainson and marketing manager Sam Hall collected the award from Chantelle Scott, leading chef and now general manager of the Gilbert Scott.
The accolade comes just over a year since the former Von Essen venue was sold to private buyers for just under £6m.
Speaking to BigHospitality, Hall said while the team had been quietly confident of success they were still 'nicely surprised' to have been crowned winners.
"We have recently employed a new chef in the last four or five months and we were expecting him to have an impact but we are pretty delighted with the impact he has had so far."
A Britain's Best Dish finalist, 30-year-old Swainson joined The Samling from another former Von Essen property - Seaham Hall in County Durham. He has also worked as acting head chef at Alan Murchison's Michelin-starred restaurant L'Ortolan and under Will Holland at La Bécasse.
"We know how good he is but for him to achieve that is pretty staggering," Hall said of Swainson's role in the win for The Samling.
"We were still surprised that we managed to turn it around in such a short space of time. It was the creativity of his menu - he offered something different."
The judges also praised the use of local ingredients and the service at the 11-bedroom hotel as well as the menu knowledge of the front of house team.
Hall revealed the hotel's owners had now completed a year of bringing in new, young talent to the team and would now embark on a year of on-site developments, soon to be revealed. "I do think The Samling will be the hotel that people will be talking about in 2013," Hall concluded.
Boutique Hotel Awards 2012
Other UK hotels celebrating after the winners in this year's Boutique Hotel Awards were announced were Sanctum Soho and The Ampersand which were both named as runners-up in the Best Design Boutique Hotel in the World and Best New Boutique Hotel in the World categories respectively.
The full list of winners of the Boutique Hotel Awards 2012:
Best Beach Boutique Hotel in the World
- Winner: Hansar Samui, Koh Samui, Thailand
- Runner-up: Layana Resort, Koh Lanta, Thailand
Best Classic Boutique Hotel in the World
- Winner: Poseidonion Grand Hotel, Spetses, Greece
- Runner-up: Hotel Les Ottomans, Istanbul, Turkey
Best City Boutique Hotel in the World
- Winner: The Toren, Amsterdam, Netherlands
- Runner-up: Lydmar Hotel, Stockholm, Sweden
Best Design Boutique Hotel in the World
- Winner: Casa Colombo, Colombo, Sri Lanka
- Runner-up: Sanctum Soho, London, UK
Best Dining Boutique Hotel in the World
- Winner: The Samling Hotel, Windermere, UK
- Runner-up: Xara Palace, Mdina, Malta
Best Honeymoon Boutique Hotel in the World
- Winner: Taveuni Palms Resort, Taveuni, Fiji
- Runner-up: The Pavilions Phuket, Phuket, Thailand
Best New Boutique Hotel in the World
- Winner: Entre Cielos, Mendoza, Argentina
- Runner-up: The Ampersand, London, UK
Best Overall Boutique Hotel in the World
- Winner: Borgo Santo Pietro, Tuscany, Italy
Nominations for the 2013 awards are now open with two new categories for next year - Best Eco Hotel and Best Spa Hotel.