The Alice In Wonderland star, who was born in the British capital, was awarded the unusual accolade at a ceremony on Wednesday (04Aug10).
The honour, which dates back to the 13th century, historically allowed the recipient a raft of bizarre freedoms - including the right to a free drink in all pubs, to drive sheep over London Bridge and to carry a sword.
And Windsor is delighted her hometown has recognised her in such an eccentric manner.
She says, "This is a wonderful moment; the freedom to the best city in the world, and the one I was born in and love and adore."
The 72-year-old blonde is best known in the U.K. for starring in the Carry On Films and her longrunning role in hit soap opera EastEnders, which she will leave later this year (10).