The Ayr, Carrick and Cumnock MP announced her resignation at a full council meeting in County Buildings on Thursday.
She said: "It has been an honour and privilege to serve my ward and South Ayrshire.
"This particular chapter is now closed and I look forward to the challenges my new role will bring but there's one thing I can guarantee —the people of Ayr East and Ayr, Carrrick & Cumnock will always be at the heart of everything I do.
"Hopefully my links with the council will help in my new role and I look forward to working closely with South and East Ayrshire to help the constituency reach its full potential."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article