Ms Dartington will lead the compliance team and ensure regulatory obligations are met by the national and its partners.
She joins Sandringham from 2plan where she was director of regulation for over five years and was a founder of the senior management team.
Ms Dartington said: "I am delighted to be taking on the role of compliance director for Sandringham Financial Partners. It is a very exciting opportunity to join the company at the very beginning and I have lots to contribute to the development of the business."

She is the second senior appointment at the firm, which is managed by Steve Braidford and set up by Ken Davy, founder of the SimplyBiz group.
Earlier this month, John Hayden was appointed to the role of operations director. He joins from his role as product and services director at Intrinsic and will be responsible for ensuring the smooth running of the Sandringham organisation.
Mr Hayden said: "It is incredibly excited to be joining Sandringham Financial Partners at such an embryonic stage, it is a fantastic opportunity for me.
"One of my key focuses will be the development of the client proprosition which is going to be first class and unique in the marketplace. I'm thoroughly looking forward to helping to bring Sandringham to the market."