Developed in 2011, the 10-acre site comprises 44,000 square feet of selling space, parking for 650 and an eight-pump petrol filling station.
It has an unexpired lease term of 15 years with five-yearly rent reviews subject to 2% fixed annually compounded uplifts.
The acquisition includes the next-door Homebase unit, which has a net sales area of 33,000 square feet and an unexpired lease term of 10 years.
Based on the cost of the deal, the combined net initial yield is 6.6%.
Ben Green, of Atrato Capital, the investment adviser to Supermarket Income REIT, said: "This income accretive acquisition is our first in Northern Ireland, adding further geographical diversification to our growing portfolio of UK supermarkets."
The company is a real estate investment trust providing secure, inflation-protected, long income from grocery property in the UK.