Henry Lewis was given the royal honour by the Duke of Cambridge for his services to fundraising and charitable causes.
The centenarian stood up from his wheelchair to collect the medal.
Afterwards, Mr Lewis was visibly touched as he told the PA news agency: “It’s all very nice and I’m very pleased about it.
“I’m very surprised I ever got it”.
Mr Lewis said magic has allowed him to fundraise throughout his life.
He said: “Magic was a hobby of mine, it’s never been my profession, but it’s raised a lot of money all over the world.
“I performed in Canada. I performed in Denmark; Israel; in Massachusetts in two very large theatres. So I’ve had a very, very good life compared to most and I’ve done a lot in it.”
The best part of magic is that people enjoy it
Asked if he still did magic, Mr Lewis said he recently put on a show at the assisted living facility in North London where he lives.
He joked: “They complained about it. It was too short.”
Mr Lewis, whose interest began when he found a magic book in a pile of rubbish in Hackney, east London, as a youngster, then showed off his skills.
He pulled out a white handkerchief, stuck a safety pin in one corner, and pulled it through to other side of the cloth without unfastening it.
He said: “The best part of magic is that people enjoy it.”
Asked about his secret to a long life, Mr Lewis said: “Not to be devious. Go to bed at night, think of what you’ve done during the day.
“Think of what you’ll be doing the next day and when you wake up, do it.
“And never be jealous or envious of other people or their possessions.
“If you’re like that you’ll be happy.”
Meeting William was not Mr Lewis’ first royal encounter.
As honorary vice president of The Magic Circle, he said he met the Prince of Wales while performing at the famous society.
Mr Lewis was also president of the Inner Magic Circle and a member of the Society of American Magicians
He is a Fellow of the Royal Institute of Chartered Surveyors and of the Incorporated Society of Valuers and Auctioneers.