She replaces former Channel Islands Society Chief Executive Allan Smith, who lost his board place in the recent elections.
Ms Lidbetter, Chief Executive of Lincolnshire Co-operative, joined the Group board last year and in her new role, will also chair the Food Board.
She is one of three Deputy Chairs, the other two being Paul Flowers who chairs Co-operative Financial Services and Steve Watts who chairs the Specialist Business Board.
Group Chair Len Wardle said: “We welcome the appointment of Ursula as the new Group Deputy Chair. The Food Board has an important part to play in the governance of the Group and Ursula will bring strong commercial and co-operative experience to this role.”