The medieval monarch’s skeleton was found in Leicester City Council’s car park in 2012 during an archaeological excavation, and DNA from living descendants was used to confirm it was him.
Greyfriars will now be a “scheduled monument”, meaning special consent will be needed before any changes could be made.
Richard III was hastily buried after his death at the Battle of Bosworth in 1485. He was reburied in 2015 at Leicester Cathedral.
Archaeologists believe the site, which has been called “one of the most significant in our national history”, is well preserved and could yield more archaeological remains.
Although parts of the site have been built on, most of it has remained gardens or car parks, all close to the council’s buildings.
The site dates back to the 1220s, when Franciscan friars set up their church, which was where Richard III’s body was originally laid to rest.
It is believed the friary was knocked down when Henry Tudor, who became King Henry VIII after the battle, broke with the Catholic Church in Rome.
Heritage minister John Glen described the discovery of Richard’s remains “an extraordinary archaeological find and an incredible moment in British history”.
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He added: “By protecting this site as a scheduled monument, we are ensuring that the remains of this once lost medieval friary buried under Leicester are preserved for future generations.”
The protection status was granted by the Culture Department on the advice of government heritage agency Historic England.