Bonham Carter received the award during a Buckingham Palace investiture ceremony but spoke only briefly to the waiting press after receiving the honour.
The actress was dressed in a striking red tartan patterned dress and had a miniature top hat perched on her head.
The actress on the redcarpet on an earlier occasion with husband Tim Burton
It was while filming the re-make of Planet Of The Apes that she met her partner, director Tim Burton, and she has gone on to star in several of his films including Charlie And The Chocolate Factory and Alice In Wonderland.
The couple, who have two children, were photographed last year enjoying a New Year's Day walk with Prime Minister David Cameron and his wife Samantha, and were believed to have seen in the new year at Chequers.
Bonham Carter is no stranger to political circles. She is the great-granddaughter of former Liberal Party leader and prime minister Herbert Asquith and her uncle Mark Bonham Carter was a Liberal MP.
Bonham Carter was joined by Tim Burton at the ceremony and their two young children, son Billy Ray, aged eight and four-year-old Nell.
Bonham Carter with Colin Firth and Geoffrey Rushatthepremiere of The King's Speech
The couple, who are said to live separately in adjoining houses in London, met the Queen last week when she hosted a reception to mark the 200th anniversary of Charles Dickens' birth as the actress plays Miss Havisham in a new film version of Great Expectations.
In the palace courtyard Bonham Carter was relaxed and chatted with the family members of other honours recipients and posed for pictures.
The Hollywood star agreed to be photographed by the waiting media but did not want to be interviewed, and would only say when asked about her big day that it was "very, very special".