The Liberals' political donation scandal has helped hand NSW Labor two by-election wins in the state's Hunter region.

Newcastle councillor Tim Crakanthorp and Lake Macquarie mayor Jodie Harrison were victors in Newcastle and Charlestown yesterday, and have pledged to restore trust in their new electorates.

The seats were vacated in August after the resignations of Liberals Tim Owen and Andrew Cornwell, who admitted to the corruption watchdog they received banned donations.

The Liberal Party didn't run candidates in either by-election.