Dong has sold this part of the business to the Ineos Group, a UK-based petrochemicals firm.
The deal is made up of a DKK 7 billion unconditional payment and contingent payments totalling DKK 1.7 billion.
Dong has for a long time signalled its exit from oil and gas.
"Since the decision in 2016 to divest our upstream oil and gas business, we've actively worked to get the best transaction by selling the business as a whole, getting a good and fair price for it and ensuring the optimal conditions for the long-term development of the oil and gas business. With the agreement with Ineos, we've obtained just that," Dong Energy CEO Henrik Poulsen said,
"The transaction completes the transformation of Dong Energy into a leading, pure-play renewables company," Poulsen added.
The transaction is expected to close in Q3 this year, at which point 440 Dong employees will also be transfered to Ineos.