The role was created as part of the agency's bid to boost its strategic credentials following the restructuring of its operations, announced in April.
Douglas, who left Publicis last November, joins MindShare from its sister creative agency JWT, where he was the head planner on its HSBC business. He will also run MindShare's newly created business planning group alongside Simeon Duckworth, the futures director, who has been promoted to become the joint head of the unit.
The agency's restructure, which will be completed in the UK by the end of the year, involves the merging of 12 agency business units into four, one of which is the business planning group.
Jed Glanvill, the chief executive of MindShare, said: "Kim has one of the best backgrounds in the business, and is a top-flight planner who will help us identify our clients' business issues, as well as inspire creative and strategic excellence across the agency."
The arrival of Douglas, who will join in November, follows the departure of the previous joint heads of strategy, Richard Armstrong and Anthony Edwards, who, along with Mark Webster, the head of content and sponsorship, are leaving to launch a branded content agency, Kameleon.
Backed by the independent TV production group All3Media, it will work with the group's production companies, which make shows such as Shameless and Hollyoaks.