Hardy has extensive, more than 25 years, experience in civil engineering and currently holds a part time executive role at Skanska, as well as non-executive roles at government backed Ebbsfleet Development Corporation and the Defence Infrastructure Organisation.
She was previously infrastructure director at CLM, which was part of the consortium that delivered the London 2012 Olympics.
In her role at Sirius Minerals Hardy will be non-executive director. At the same time Stephen Pycroft is leaving the board after two years, as he has increasing work commitments (as chairman of construction consultant Mace).
"Louise Hardy brings a wealth of experience in delivering large-scale construction projects and we are delighted to add her to our board,” said Sirius Minerals chairman Russell Scrimshaw.
Pycroft added: “"I'm proud to have been part of an exciting period at Sirius, during which time major steps forward have been achieved in the development of its North Yorkshire polyhalite project.
"Whilst I am disappointed to be leaving the board at this exciting time, I have known Louise Hardy well since Mace's involvement in the delivery of the London Olympics and I am delighted to support her appointment to the Sirius board.”
Pycroft said he will remain a shareholder of Sirius Minerals, and will act as an advisor to the company.