Britain's Duke and Duchess of Sussex are today celebrating their one year wedding anniversary.

The royal couple married on May 19, 2018 in a star-studded ceremony at St George's Chapel in Windsor that was watched by millions around the world.

Prince Harry and Meghan Markle marked the occasion on Sunday by releasing a video compilation of black-and-white wedding photographs, including some that have never been seen before, on their official Instagram account.

The one-minute long montage includes pictures of the couple signing the register at St George's Chapel, a candid shot of Prince Harry and best man Prince William walking down a staircase, and Markle holding hands with her mother Doria Ragland.

The video is accompanied by the song This Little Light Of Mine, which played as they left the chapel on their wedding day.

In the post, the couple thanked their followers for "all of the love and support from so many".

A message published with the picture reads: "Happy one year anniversary to Their Royal Highnesses, The Duke and Duchess of Sussex!

"Today marks the one year anniversary of the wedding of The Duke and Duchess of Sussex.

"Their Royal Highnesses exchanged vows at St George’s Chapel within the grounds of Windsor Castle on May 19th, 2018.

"The selected song 'This Little Light of Mine' was chosen by the couple for their recessional.

"We hope you enjoy reliving this moment, and seeing some behind the scenes photos from this special day.

"A message from The Duke & Duchess: 'Thank you for all of the love and support from so many of you around the world. Each of you made this day even more meaningful.'"

Meghan Markle and Prince Harry thanks followers for "all the love and support"

They are celebrating their first wedding anniversary as a family of three following the arrival of their son Archie earlier in May.

The royal couple introduced their newborn baby to the world in St George's Hall in Windsor Castle, with Markle saying: "It's magic, it's pretty amazing. I have the two best guys in the world so I'm really happy."

Meghan Markle and Prince Harry introduced Archie to the world earlier this moth

Archie was born on Monday May 6 at 5:26am weighing 7lbs 3oz and is seventh in line to the British throne.

The couple met on a blind date in July 2016 and had a whirlwind romance before announcing their engagement in November 2017.