Councillor Colin Clark of Inverurie and District Ward has formally resigned from the post following his election as an MP last month.
Cllr Clark had served on Aberdeenshire Council since November 2016 and his resignation was accepted on Monday.
He said: “I have enjoyed my time representing the people of Inverurie whilst at the Council and I am looking forward to representing them and the rest of Gordon at Westminster.”
Jim Savege said: “I thank Cllr Clark for his service. He will continue to serve his constituents at Westminster, so his links with Aberdeenshire Council will remain strong.”
Plans are now being put in place for a by-election on October 12, with the Count taking place the following day.
Further details will be announced once arrangements have been confirmed.