Hitmaker Pharrell Williams has apologised for donning a Native American headdress on the cover of UK magazine.

The Happy singer caused controversy when UK ELLE unveiled its July cover, showing Williams in profile wearing a large feathered headpiece.

While the magazine's website proclaimed the 41-year-old had "never looked so good", some commenters had to disagree.

"You mean ELLE and Pharrell (have) never looked so blatantly ignorant," Johnnie Jae wrote.

Others slammed the cover for tastelessly appropriating a spiritual garment as a fashion accessory, while the hashtag #nothappy cropped up on Twitter.

Playing or Trending on Indian Culture is so disrespectful #ShowSomeDignity #pharellwilliams #Pharrell #NotHappy #Stop pic.twitter.com/3qJZoYuhT8

— Pamela J.

Peters (@NavajoFilmmaker) June 4, 2014

#nothappy @PharelI A little education goes a long way! A headdress is traditionally for a chief not a #chump

— Aly Charles (@OronhiaAly) June 4, 2014

In a statement from his publicist, Williams apologised for the cover.

"I respect and honour every kind of race, background and culture," he said. "I am genuinely sorry."

Last month, the N.E.R.D frontman defended a group of Iranian youths who were arrested for posting a video of themselves dancing to his hit song, Happy.

Last month John Key's daughter Stephanie attracted controversy when she wore a Native American headdress in a photo that was part of her university art portfolio.

- AAP