Ms Willmott will take up the role in the first quarter of next year.
She has recently been working as director of external relations for Fortescue Metals Group, a role she took on in 2010.
It is believed she has chosen to move to a new role after helping FMG complete all approvals for its planned production expansion to 155 million tonnes per year.
“Deidre’s unique skill set is a perfect fit with Cannings Purple’s core business offerings, which are highly geared to the resources, energy and related professional services sectors,” Mr Hazeldine said in a statement.
“In particular, Deidre brings extensive knowledge of both state and federal government, including strong experience in project approvals, which will be of tremendous value to our resources and energy sector clients.”