Designed by the College of Arms in London, the ornamental emblem combines the couple's separate shields.
It was approved earlier this year by William's grandmother, Queen Elizabeth II, and unveiled Friday, the magazine said on its website.
William's shield was granted by the Queen on William's 18th birthday and Kate's was presented to her in 2011 shortly before she wed the prince.
Kensington Palace said in a press release the coat of arms will be the couple's forever.
"However, as their circumstances and roles alter, elements of the accouterments around the shields may change," the statement said.
William is second in line for the British throne behind his father Prince Charles.