The group, which is calling for an end to oil and gas deals, said it carried out the vandalism to pressure supermarkets into reducing the prices of baby products, and called on the Scottish Government to fund a community food hub for 500 people.
It follows a court case last week which saw several This Is Rigged protestors walk free after being admonished for disrupting the UCI World Cycling Championships over the summer by gluing themselves to a road near Falkirk.
A spokesman for Historic Environment Scotland said: “We can confirm that there was a small disturbance in the Crown Room at Edinburgh Castle earlier today and police were called to the scene.
“There has been some damage to the protective glass housing the Honours, however the casing was not breached and the Honours themselves were not damaged. The Castle remains open, however we have temporarily closed the Crown Room and Royal Apartments.”