Fertiliser company Sirius Minerals is ploughing £2.4bn into the York Potash Project to build the mine in the national park, just south of Whitby.
The project will create more than 1,000 jobs when it reaches full production and a further 1,500 jobs indirectly, the company said.
The mine will also make a yearly contribution to UK GDP of £2.3bn, according to economic modelling carried out by the firm.
Business leaders said it is the biggest private investment project in the North of England "by a billion miles."
But it is hugely controversial and environmentalists and organisations including the Campaign to Protect Rural England (CPRE) and the National Trust campaigned against it.
Sirius chief executive Chris Fraser said: "The business that is created from this project will sit as a world leader in the fertiliser industry based here in the UK.
"It is expected to have a low operating cost structure, high margins and a very long asset life in one of the most business-friendly, stable and dynamic economies in the world.
"In delivering this project we can create thousands of jobs in North Yorkshire and Teesside, deliver billions of pounds of investment to the UK and put the country at the forefront of the multi-nutrient fertiliser industry."
The project will see a 4,921ft mine sunk beneath the park, which will tunnel outwards and pump the mineral polyhalite - a speciality fertiliser - underground around 30 miles (48km) north to Teesside, where it will be processed.
It is expected to go into production in 20202021.