The 18-bedroom hotel and restaurant, situated in a Grade II listed building in Wales' 'book capital', will remain open until next January when it will partially close for refurbishment.
Calum Milne, managing director of Llangoed Limited, said work would include refurbishing the bedrooms and replacing the roof to 'bring the property up to a more comfortable standard'.
“We expect to complete the refurbishment by the end of April 2016 when it will be a very comfortable coaching inn offering very good food," he said.
All 15 of the hotel's full and part-time members of staff are being retained as part of the deal with a new manager and head chef in the process of being appointed.
Milne said the company, which plans to expand further this year, saw the Swan at Hay as a good fit for the group.
“The Swan at Hay Hotel fits nicely in its locale and offers another price point for our customers and an alternative dining experience for guests at Llangoed Hall.
"We will not be taking the dining experience to the same level as Llangoed Hall as there is no point in creating competition unnecessarily, but The Swan at Hay Hotel will be serving very good food and certainly some good, old classics."
He said he hoped to make the venue more attractive to visitors to the Hay Festival, which attracts thousands of book fans each year, as well as make it a space to accommodate Llangoed Hall's wedding guests.
“Because of the successful growth of weddings at Llangoed Hall, we need to expand the number of bedrooms that we are able to offer to our guests and the acquisition will give us a much stronger base for the Hay Festival next year," he said.
Milne, who has transformed the future of former Von Essen hotel Llangoed Hall since rescuing it from administration in 2012, said the company was continuing to look for other properties. Following the acquisition of Llangoed Hall it bought the 49-bedroom hotel Sudbury House in Oxfordshire and wants to grow further.
"We have no intention of standing still, as we wish to be leaders in raising the standard of hospitality in Wales,” he said. “The group will look at further expansion in the near future.”