Regional returning officer John Itanu declared Momis president-elect at the weekend, with Bougainville media reporting that the president said he acknowledged the mandate given to him by the people.
He also said that despite minor setbacks during the election period, voters conducted themselves peacefully and showed their commitment to the democratic process.
A feature of the 2015 general election was that it was first one which conducted by the region's own electoral commission.
Elected candidates will be sworn into the Bougainville House of Representatives on June 15.
The ballots were counted in Hutjena, Arawa and Buin, and a limited preferential voting system was used.