Kate MiddletonandPrince Williamhave returned to a staple on the royal calendar — this time, with new titles.

For the first time since becoming the Prince and Princess of Wales following the death ofQueen ElizabethandKing Charles' accession to the throne in September, the couple attended the annual Commonwealth Day Service on Monday. The event took place at a special place for Prince William, 40, and Princess Kate, 41: Westminster Abbey, where they exchanged vows on their royal wedding day in April 2011.

Princess Kate arrived in a navy Erdem peplum jacket and skirt with a white embroidered print. She completed the look with a navy hat and pumps, adding a little sparkle with a pair ofsapphire and diamond earringsthat previously belonged toPrincess Diana.

She also accessorized with a Prince of Walesfeathers brooch, which was a gift from King Charles.

Tim Rooke/Shutterstock

Catherine Princess of Wales and Prince William Commonwealth Day Service at Westminster Abbey

Carrying navy gloves and a clutch as she walked into Westminster Abbey, Kate had to hang on to her hat to save it from flying away in a gust of wind.

Catherine Princess of Wales and Prince William Commonwealth Day Service at Westminster Abbey

Others members of the royal family in attendance included King Charles andQueen Camilla,Prince EdwardandSophie(thenew Duke and Duchess of Edinburgh) andPrincess AnneandVice Admiral Sir Timothy Laurence.

JORDAN PETTITT/POOL/AFP via Getty Images

Catherine, Princess of Wales reacts as she departs after attending the Commonwealth Day service ceremon

The service honors the 56 countries and nations around the world that make up the Commonwealth. “Working in collaboration towards shared economic, environmental, social and democratic goals, the Service seeks to highlight a vast community which spans every geographical region, religion and culture, embracing the diversity of it its population of 2.5 billion people, of which over 60 percent are under 30 years old,” the palace said in a statement.

The Commonwealth Day theme for 2023 is “Forging a Sustainable and Peaceful Common Future.”

Kate Middleton, the Princess of Wales.Chris Jackson/Getty Images

Catherine, Princess of Wales with a bouquet of flowers smiles as she departs the 2023 Commonwealth Day Service at Westminster Abbey

Sustainability is a key cause for King Charles as he leads the service for the first time as monarch, including with a speech. In 2022, the then-Prince of Wales gave an address on behalf of his mother,Queen Elizabeth, whomissed the service.

PHOTO: Chris Jackson/Getty ImagesPHOTO: Tim Rooke/Shutterstock

Prince William, Prince of Wales and Catherine, Princess of Wales smile as they depart the 2023 Commonwealth Day Service at Westminster Abbey

Catherine Princess of Wales and Prince William Commonwealth Day Service at Westminster Abbey

The service began with a procession of Commonwealth member states' flags. As 2023 is the Commonwealth Year of Peace, a specially-designed Commonwealth Flag for Peace was also processed.

The event included musical performances from saxophonist Yolanda Brown, West End stars Roshani Abbey and Nuwan Hugh Perera and the all-female Amalgamation Choir from Cyprus. Marking Rwanda’s role as the current Commonwealth Chair-in-Office, the Rwandan National Ballet, Urukerereza, also performed.

Hannah McKay/AP/Shutterstock

King Charles III, Camilla, the Queen Consort, Britain’s Prince William, and Kate, Princess of Wales attend the Commonwealth Day service held at Westminster Abbey

Can’t get enough ofPEOPLE’s Royals coverage?Sign up for our free Royals newsletterto get the latest updates on Kate Middleton, Meghan Markle and more!

Last year marked a return to the Commonwealth Day Service, which wascanceled in 2021due to the coronavirus pandemic and replaced with a smaller event.

King Charles III (2L), Britain’s Camilla, Queen Consort (4L), Britain’s Prince William, Prince of Wales (5L) and Britain’s Prince Edward, Duke of Edinburgh (C), Britain’s Catherine, Princess of Wales (4R), Britain’s Princess Anne, Princess Royal (3R), Britain’s Sophie, Duchess of Edinburgh (2R) and Vice Admiral Timothy Laurence attend the Commonwealth Day service ceremony, at Westminster Abbey

The 2020 service was alsoMeghan MarkleandPrince Harry’slast joint appearance with the familybefore they stepped back from their positions as working royals and relocated to California. They have since returned to the U.K. for Queen Elizabeth’s Platinum Jubilee celebrations in June 2022 and the late monarch’s funeral events in September. Prince Harry also attended his grandfather Prince Philip’s funeral in April 2021.

source: people.com