It captioned the snap: “Today, The Duke and Duchess of Sussex’s son Archie was christened at Private Chapel at Windsor Castle.”
Prince Charles was present, as were Lady Sarah McCorquodale and Lady Jane Fellowes, relatives of Princess Diana.
Meghan looked stunning in a white dress, recaputing her bridal glow.
However, it was an undeniably brave colour choice for a woman who would be holding a baby all day.
Kate Middleton looked stunning in a coral dress with a pussy bow collar and red heels, with a red headband.
Harry wore a pale suit with a light blue tie and brown shoes, but one Twitter user criticised the look.
They wrote: “Charles and William appropriately dressed in dark suits. Harry looks the usual mess – inappropriate light suit paired with brown suede scuffed shoes and black socks??”
Another agreed, and said: “It looks terrible.”
But others stuck up for elements of the Prince’s style choice.
One wrote: “It’s entirely appropriate to wear a celebratory light suit here. The shoe/sock mismatch is pretty bad though.”
However, another Twitter user called this criticism of Harry “pathetic”.
Others had kinder things to day. One wrote: “What a gorgeous pic! Love Mama Doria’s outfit. Meghan is glowing. Harry looks awesome and omg little Archie is so adorbs!!!”
Another addressed the couple’s desire to keep press away from the event.
They wrote: “Why the privacy surrounding this family event triggered everyone is beyond me! Beautiful photo.”
A number of Twitter users commented on how Archie appears to share his father’s red hair.
One said: “Prince Archie is a beautiful baby like his parents and has his daddy’s ginger hair.”
Another said: “Has daddy’s red hair.”
Kate Middleton posed in Archie’s christening photo, and fasn could not help but stunning on how beautiful she looked.
Kate, 37, beamed in a pale pink gown, with a pussy bow tie neckline and a waistband which showed off her stunning figure.
It was a similar colour to the headpiece of Meghan’s mother, Doria Ragland, who was also pictured at the back of shot.
Mum of three Kate chose dark red heels and a matching headband to finish off her fashionable look.
Who is Meghan Markle? Quick profile
Meghan Markle was born Rachel Meghan Markle, on August 4, 1981 to parents Doria Ragland and father Thomas Markle.
Her father was previously married to Roslyn Loveless and Meghan has two elder half sibling – sister Samantha Markle and brother Thomas Markle Junior.
Meghan’s first television appearance in the USA was in an episode of the medical drama General Hospital in 2002.
She later moved on to roles in CSI, Without a Trace and Castle along with bit parts in Hollywood films including Get Him to the Greek, Remember Me and Horrible Bosses.
Meghan was also a “briefcase girl” on Deal or No Deal – but her most famous role was as Rachel Zane in legal drama Suits, which launched in 2011.
She was written out in the finale of the seventh series when her character got married, which aired in April 2018 – just before she got married herself.
Charity and humanitarian work
Meghan Markle’s career in television has gone hand-in-hand with her support for causes close to her heart.
She wrote about the stigma around menstrual health in an article for Time magazine and was a Global Ambassador for World Vision Canada – with whom she travelled to Rwanda for the charity’s Clean Water Campaign.
And her commitment to gender equality has seen her work with the United Nations – receiving a standing ovation in 2015 for her speech to mark International Women’s Day.
In September 2011, she wed film producer Trevor Engelson, who she began dating in 2004.
But the pair divorced two years later in August 2013, citing irreconcilable difference.
She was in a relationship with celebrity chef Cory Vitiello for almost two years, before they broke it off in 2016 but the two remain good friends.
And in June 2016, she met Prince Harry on a blind date set up by a mutual friend.
Their relationship began in October that year and just over one year later, on November 27, 2017, the pair announced their engagement.
They married on May 19, 2018 at St George’s Chapel in Windsor Castle.
Some have claimed Meghan Markle is the first mixed-race member of the Royal Family.
Historians are still arguing about Queen Charlotte, the wife of King George III.
But Meghan will be the first royal to openly embrace a mixed-race heritage.
She has written about the difficulties of being a biracial actress in Hollywood as she claims she is not black enough for some roles and not white enough for others.