The deal was first flagged in May last year.
Gregory Crinum is a hard coking coal open cut and underground operation, 60 km northeast of Emerald in the Bowen Basin.
The project has been on care and maintenance since 2016 when coal prices dipped, but had been producing up to 6 million tonnes per annum at that time.
BMA Asset president James Palmer wished Sojitz well in its plans to restart Gregory Crinum.
"This will provide new job opportunities and trade benefits for the people of central Queensland, as well as increased royalties and taxes to benefit the state," he said.
BMA made the decision to sell the mine after a detailed review concluded there was potential for another party to realise greater value from the asset.
In addition to the sale of the mine, BMA is providing appropriate funding for rehabilitation of existing areas of disturbance at the site, with all rehabilitation liabilities transferred to Sojitz, though the net impact from this funding is not material for BHP or Mitsubishi.
BMA is a 50:50 joint venture between BHP and Mitsubishi Corporation.
Mitsubishi said the sale was part of steps it had taken to improve its asset portfolio.