The tartan comes a year after South Uist gained official recognition for its flag with the design now officially registered.
The tartan was designed by former councillor Donnie Steele with the weave based on the green, black, blue and white of the South Uist flag.
Mr Steele told Hebrides News: “Since the flag recognition I have been working on innovative ideas that can enhance South Uist and the surrounding Islands.
“To have the tartan officially recognised by the tartan authority is another enormous boost for the Island and can only enhance the name and brand of South Uist.
“Discussions with our community landlord Storas Uibhist and key stakeholders such as community councils were very positive, and the green light was given to drive this forward.”
Mr Steele co-owns Uist Gifts with the firm to give a percentage of profits from the tartan to local good causes, according to reports.
Last year, South Uist secured the first officially recognised community flag in the Outer Hebrides.
The blue Nordic cross design is held by the Court of the Lord Lyon.
The tartan is the fourth to registered to South Uist with the new tartan and is the latest enterprise from the island whose residents embarked on the biggest community land buyout to date in 2006.