Town of Port Hedland Mayor Peter Carter has resigned with immediate effect.
He said his decision was not made lightly, and comes after thorough consideration of his options.
His resignation leaves the Council without a quorum for the second time in six years.
The Town said it is awaiting advice from the Department of Local Government on next steps.
In May this year, Local Government Minister Hannah Beazley said she had commenced groundwork to install a commissioner if required, after a four councillors resigned in a six month.
The Council has been operating with the minimum number of five councillors since that time.