NEW YORK—Willis Group Holdings Ltd. said Friday that its shareholders have approved changing the domicile of the broker’s parent company from Bermuda to Ireland.

The reorganization would establish a new public limited company in Dublin, Willis Group Holdings P.L.C., to replace Wills Group Holdings Ltd. as the ultimate parent of London-based Willis’ operations.

With shareholder approval, the proposal to reorganize the company now goes before the Supreme Court of Bermuda. If the Supreme Court of Bermuda approves the change at a Dec. 18 hearing, Willis said it expects the reorganization of the company to be completed by year-end.

Willis has said it wants to move its domicile for a more stable tax environment.