Julie Muldowney from Kilkenny took second place, while Helen Hayes of North Tipperary Macra, was third.
The overall winners were announced at midnight last Sunday night at a gala banquet in Dundrum House Hotel, Co Tipperary.
Susan follows in the footsteps of Bríd Cooney, the 2014 International Miss Macra, who represented the Avondhu region, Co Cork.
Susan, who beat off stiff competition from 24 other contestants, was presented with a specially-made sterling silver tiara, a Miss Macra trophy, and a cash prize. Julie and Helen were awarded runner-up prizes.
Susan, 19, a student at Carlow Institute of Technology, is a member of Tullow Macra, and hails from the village of Ballon.
Every August bank holiday, Clonoulty-Rossmore Macra hosts the festival.
Every person involved in the planning and organising of the festival does so on a voluntary basis.
The event was sponsored this year by Dundrum House Hotel and Golf Course, Joan and Michael Carew Jewellers, FBD Insurance, and Tipperary Co-op.
Events kicked off last Friday, when the contestants met the festival committee in Dundrum House Hotel before going on a personal tour of the world-renowned Coolmore stud farm.
The finalists were then treated to lunch before taking part in a zumba class and meeting their host families.
The theme for the Friday night’s fancy dress was cowboys and Indians, and allowed the finalists to let their hair down ahead of a busy Saturday, which saw each finalist interviewed by judges Joan Pollard Carew, Declan Ryan, and Noirín Ryan Forrestall.
Later, each contestant was interviewed on stage by Mike Egan at the festival marquee.
Sunday started with the contestants attending a special Mass in Clonoulty parish Church.
They then had to prove their worth by taking part in a sports day in the local GAA grounds.
Contestants and their escorts posed for the cameras before enjoying a champagne reception, followed by a five-course meal as part of the Gala Banquet.
The meal was followed by speeches, including an address by Macra president Seán Finan, live music and dancing, before Susan was crowned at midnight.