The fundraise comprised a placing and a subscription at 0.16p per share.
David Bramhill, Union Jack’s executive chairman, said he was delighted with the outcome, which he said laid a platform for further development of the AIM-listed group.
"The company is already funded for the imminent drilling at West Newton and for the associated Extended Well Test activities and the cost to first oil production at the Wressle development.
“With the fundraising net proceeds, our cash position increases to approximately £11mln and will assist in funding our next stage of growth.
"We also believe there will be attractive acquisition opportunities available from the ongoing fallout resulting from COVID, energy prices and BREXIT.”
Union Jack Oil has a range of assets under development with three flagship projects at Wressle, West Newton and Biscathorpe.