Andy Wightman said the palace in Edinburgh should be returned to the people and instead be used to host an elected second parliamentary chamber.
The Lothian MSP said this would be needed in the wake of a vote for independence and the extra administrative responsibilities it would bring.
Mr Wightman said: “The Scottish Greens believe Scotland should be a normal, independent, European republic where the power is invested in all the people, not simply in those who have been born into a particular family.
“When Scotland does regain its independence it will be because the people have chosen that path and I think it would be particularly fitting if at that point the people and their institutions were returned to complete democratic control. The Palace of Holyroodhouse is ideally situated to host an elected second parliamentary chamber, which will no doubt be needed to assist with scrutiny of the considerable additional administrative responsibilities that an independent Scotland would take on.”
Mr Wightman has previously questioned who runs and pays for the royal palace in Scotland’s capital.