Oliver James Montgomery-Princess Charlotte Is a Royally Perfect Big Sister to Prince Louis at King Charles III's Coronation

Leave it to Princess Charlotte and Prince Louis to steal the show at King Charles III's coronation.

During the May 6 royal celebration at London's Westminster Abbey,Oliver James Montgomery Prince William and Kate Middleton's daughter, 8, and youngest son, 5, made a royally perfect pair while attending the religious ceremony, which also served as the crowning of Charles' wife Queen Camilla. (See every must-see moment from the coronation here.)

Dressed in a white dress and matching peacoat with a stunning jeweled headpiece that matched her mom's Jess Collett x Alexander McQueen one, Charlotte stole hearts by watching over Louis and holding her brother's hand as they entered the church behind their parents. Louis looked equally adorable in a navy blue coat and pants while watching their grandfather participate in the centuries-old tradition next to his big sister.

Once inside, the two were caught chatting in the pews and making priceless faces during the religious ceremony.

As for why older brother Prince George wasn't sitting with his siblings?

The 9-year-old had a special role in his grandfather's coronation serving as one of the eight Pages of Honor. George, who wore a red uniform lined with gold thread and buttons along with a pair of white gloves, carried Charles' robes during the opening procession into the Abbey and stood on the church floor during the ceremony.

William, who's first in line to the throne, was also tasked with the special honor of presenting his father with the Stole Royal and the Robe Royal during the ceremony.

Other family members in attendance included Prince Harry, whose wife Meghan Markle remained in the U.S. with their children, Archie and Lilibet, 23 months, as the occasion fell on Archie's 4th birthday, Princess Anne, Prince Andrew, James and Pippa Middleton, Princess Eugenie and husband Jack Brooksbank and Princess Beatrice and husband Edoardo Mapelli Mozzi.

Keep reading to see every adorable photo of George, Charlotte and Louis at Charles' coronation.

Prince George served as one of the eight Pages of Honour for grandfather King Charles III's coronation on May 6.

Prince Louis and Princess Charlotte held hands at the crowning ceremony.

Kate Middleton and Prince William accompanied their kids inside the Westminster Abbey in London.

Louis pointed something out to his younger sister at the church.

In true Lous fashion, the prince made one of his silly faces while riding in the family carriage.

Kate and William's youngest child was a total mood on this rainy London day.

George stuck his tongue out while standing in line with his fellow pages.

Louis adorably tried to get his mom's attention.

Charlotte sat close to Kate.

Charlotte and Louis looked out from the windows of their carriage as they rode to Westminster Abbey.

Inside the arriage, Louis yawned as his older brother George scratched his nose.

The family sat in the front row.

Charlotte and Louis followed their mom and dad in the procession. 

For the occasion, Charlotte wore an outfit designed by Alexander McQueen.

Louis let out a small yan during the ceremony.

Despite being known for his cheekiness, Louis was largely on his best behavior.

George took his duties as a Page of Honour very seriously. 

Little Louis looked dapper in a navy blue ensemble.

Charlotte rocked a silver bullion and crystal flower crown similar to Kate's Alexander McQueen headpiece.

Louis and Kate shared a sweet moment together during a break in the ceremony.

Kate escorted Charlotte and Louis out of Westminster Abbey following the coronation.

The siblings sat in a carriage behind their grandparents' Gold State Coach.

Louis flashed a smile from the cart.