Northern Ireland's Department of Environment approved plans earlier this week to add 48 bedrooms and a new leisure wing, including a swimming pool and gym, to the 75-bedroom hotel.
The company, which has invested £25m in the last 10 years to create the luxurious spa hotel, is hoping that further investment will help to secure the business's future success.
Paul Smyth, Galgorm Resort & Spa operations director said: “We’re delighted that the Department of Environment’s planning department and Environment Minister Mark H Durkan have given us the formal go-ahead to proceed with our plans to provide additional new bedrooms and leisure facilities, which will ensure that we will continue to meet the demands of our quality-focused local and international customer base.
“These plans have been carefully based on our commitment to not only grow the business further but also on our commitment to deliver a top quality offering that continually exceeds the expectations of our guests.
"When combined with the significant investment made to date, we are confident that the extra facilities will underpin future growth and ensure our guests return time and time again.”
The hotel is expected to create another 60 full and part-time jobs once work is completed in 2015.
Environment Minister Durkan whose department approved the plans, said in a statement: “This is good news for Ballymena and the surrounding area. The new addition to this award winning resort will benefit tourism in mid-Antrim, providing high quality accommodation in an area that is the gateway to the Glens of Antrim and the scenic north coast.