Green stepped down as chief executive of the Gers in May, following the launch of an internal investigation by the club into his dealings with former owner Craig Whyte.
The Glasgow club have announced Green's return in a statement to the London Stock Exchange, with his primary role to act as an advisor to shareholders and promote the club's interests.
An official statement read: "The board of Rangers is pleased to announce that it has today appointed Charles Green as a consultant to the company.
"Mr Green's role will be to promote the interests of Rangers Football Club, specifically assisting with shareholder relations and advising the company on its capital structure."
The 60-year-old remains a shareholder at Ibrox.