Pippa Middleton promotes Justin Bieber online

AP

After the wedding of Prince William and Kate Middleton, Justin Bieber showed his appreciation for the royal couple by posting a congratulatory message on Twitter.

“Congrats to William and Kate … and Kate’s sister,” Bieber wrote for his 10 million followers.

The pop sensation also described bridesmaid Pippa’s dress as being a “hit”.

The effect that Pippa had on Bieber benefited the Middleton family, who will sell Justin Bieber merchandise on an online shop, called Party Pieces, which they own.

Justin Bieber party products are promoted on the online magazine, which is produced by Pippa, with the slogan “We’ve got Bieber fever.”

Justin Bieber’s representatives have confirmed that a deal with the company Party Pieces has been signed, and that the 17-year-old singer “worked closely” on all his products.

The Justin Bieber range contains a Justin Bieber Ultimate Party Kit which includes a set of plates, cups, napkins, banners and balloons for 16 people at a price of £20.89. Also, some products, with Bieber’s face, can be purchased at cheaper prices: VIP badge necklaces, a decorative award ribbon or a piñata to hold birthday treats.

“Teenage girls around the world go crazy for Bieber. In fact, they love Justin Bieber so much that the pop star now has his very own partyware,” the article advertising for Justin Bieber reads.

The Middleton family’s business prospered since the royal wedding. A source specializing in intellectual property rights said the partnership between Justin Bieber and the Middletons is a true success.