This ornamental emblem, which represents them in heraldic terms as a married couple, was approved by the Queen earlier this year and shown publicly for the first time Friday.
Designed by the College of Arms in London, the Conjugal Coat of Arms essentially combines the separate shields of William and Kate.
And, as Katy Perry might sing, the united Coat of Arms certainly has a lot of "Roar."
The Duke's shield, granted by the Queen on William's 18th birthday (he, like Kate, is now 31), is shown on the left and features the various Royal emblems of different parts of the United Kingdom: the three lions of England in the first and fourth quarters, the lion of Scotland in the second, and the harp of Ireland in the third.
It is also surrounded by a blue garter bearing the motto "Honi soit qui mal y pense" ("Shame to those who think evil of it"), which symbolizes the Order of the Garter, of which the Duke is a Knight Companion.
The Duchess's shield, from the Middleton Coat of Arms and granted to the family in 2011 ahead of Kate's marriage, is shown on the right.
The technical heraldic description of the Middleton Coat of Arms, known as a "blazon," is "Per pale Azure and Gules a Chevron Or cotised Argent between three Acorns slipped and leaved Or."
"Per pale" means that the shield is divided vertically with one half blue (azure) and the other half red (gules). A "Chevron Or" indicates the gold chevron across the center of the shield.
For its placement in the conjugal Arms, the Duchess of Cambridge's shield is surrounded by an oak wreath to balance out the Duke’s garter, which is traditional for royal spouses who are not themselves entitled to surround their Arms with an order of chivalry.
Both shields are supported by the Duke of Cambridge's Supporters of the Royal Lion and Unicorn wearing a three-pointed collar, which features a red escallop shell derived from the Spencer Coat of Arms that has been used by the Duke's ancestors on his mother's side for centuries.
The Royal press release states that the Conjugal Arms will be the couple's forever, "however as their circumstances and roles alter, elements of the accouterments around the shields may change."