Being a foreign national Mr Giuliani can only be lined up for an honorary title, meaning that he does not receive the full sword tapping treatment or a "Sir" prefix.
The title is bestowed by the Queen, on the advice of the foreign secretary, to those non-Britons who have made an important contribution to relations between their country and hers.
First bestowed by King George V in 1917, the honorary knighthood has been handed to some very famous recipients in recent years.
In January 2001 the film director and producer Steven Spielberg was honoured by Sir Christopher Meyer, the British ambassador to the US, on behalf of the Queen.
The man behind such cinematic works as ET, Schindler's List and Saving Private Ryan, Mr Spielberg received the KBE for his contribution to the British film and entertainment industries.
Being an Irishman, Bob Geldof had to be content with an honorary title following his massive fund raising efforts for famine victims in Africa in 1985.
The former Boomtown Rats singer's Live Aid concert and number one single, Do they know it's Christmas?, raised huge amounts of money for the cause and brought the issue to the attention of the wider public.
The American evangelist Dr Billy Graham can also extend his name by three letters after receiving a KBE in December 2001.
Dr Graham has been a confidant of every US president since Harry Truman in 1945 and has had meetings with the Queen on several occasions. His honorary knighthood was awarded for his "truly international contribution to civic and religious life," according to the Foreign Office.
Pele, the man voted the greatest footballer in the history of the game by FIFA, was made an honorary knight in the build-up to the World Cup in 1998.
Pele, real name Edson Arantes de Nascimento, received the honour in his capacity as a Brazilian government minister, but is certainly a little more famous for being the outstanding player of three World Cup winning Brazil teams and scoring over one thousand goals in his professional career.
Other honorary knights include the composer and orchestral maestro Andre Previn, the oil tycoon John Paul Getty II and the British-born actor Bob Hope, who received the honour in 1976.
The former US president Ronald Reagan became an honorary knight for the close relationship he developed with Britain in his time at America's helm, as did his defence secretary, Casper Weinberger.
The former president George Bush Sr is also an honorary knight, his title bestowed upon him following his involvement in the 1993 conflict in the Gulf.
General Norman Schwartzkopf and the former head of the joint chiefs of staff (now US secretary of state) Colin Powell also both received honorary knighthoods following their combined efforts in the Gulf war.
