Mason, who will start her new role on July 31, will take over from current chief executive David Ward.
Ward will retire when his contract expires on June 30. He has been chief executive for 10 years.
Mason has more than 20 years of leadership experience in the local government, health and not-for-profit sectors.
The appointment follows a rigorous process over the past three months which attracted a large number of high calibre applicants, Mayor Sam Broughton said.
Broughton was excited to have Sharon join the leadership team.
“We had many very strong candidates apply for the role and councillors and I are looking forward to welcoming Sharon and the continued energy she will bring to our council.
"We have a lot of opportunities in the district and believe Sharon will build on the great work already under way.”
Originally from the UK, she was a registered nurse and joined the Queen Alexander Royal Army Nursing Corps as a nursing officer.
Mason says she understands the nuances of working successfully in partnership with central government, boards, elected members, mana whenua and council staff "to create a shared purpose and strong trusted links".
“I’m really looking forward to starting my role with Selwyn District Council and bringing my style and brand of leadership to the district," Mason said.
"It is a privilege to take over from David Ward whose leadership has ensured the council is in a strong position.
"I want to support the council to continue to be a great place to work while delivering on the expectations of the community."
