Newell Stores, which is based in Dungannon, has just completed construction of a 25,000 sq ft store in nearby Coalisland.
It has been described as the biggest ever single investment in the town.
The family-owned company said 150 people will be employed there. Meanwhile the existing store in Dungannon, which employs 170, will take on an extra 33 members of staff.
It is expected to open its doors on Wednesday.
"The opening of our new store will be a welcome boost for the Coalisland, creating 150 jobs in the area," Mr Conway said. "This is also a major step for our family business, which has been built up over the generations and established an excellent reputation in Dungannon.
"We were delighted with the state of the art building and the team involved in helping bring this project to completion, from the design team to the local builders who helped further highlight Coalisland companies and their skills."
Local MLA Sandra Overend welcomed the news.
"The opening of the Newell Stores supermarket will provide a real boost to the Mid-Ulster economy," said the Ulster Unionist representative.
"The creation of 150 new jobs is significant at any time, and even more so during the continued economic downturn. This ambitious project has also employed many local people in its various stages of construction, and will hopefully continue to create jobs in the future."