The charity aims to fight poverty in Uganda and it was set up in memory of Henry van Straubenzee, a close friend of Prince Harry who died at the age of 18 in a vehicle crash.
For the event, Markle wore a navy dress with a scooped neckline along with a navy jacket, and while there aren't many photos of the couple at the service, it's clear that Markle's baby bump has officially popped.
Meghan was said to have given a confident recital of Our Deepest Fear by Marianne Williamson in front of a packed congregation at St Luke's church in Kensington, west London.
Duchess Cate greets guests at an evening reception for members of the Diplomatic Corps at Buckingham Palace on December 4, 2018 in London.
The Duchess, wearing a festive black Brora cardigan and tartan Emilia Wickstead skirt, also gave a heartfelt speech in which she recognised how hard it is to be away from family members at this time of the year.
As Meghan has come under fire for her lavish wardrobe choices, it could be fairly argued that her sister-in-law has been strategically recycling almost every outfit in recent weeks, not only positioning herself as the more thrifty royal, but also ensuring the wow factor when she debuts something new, as she did last night.
The women also discussed other upcoming charity work to be carried out by Meghan as a Commonwealth Youth Ambassador which she will carry out with her husband the Duke of Sussex. Add Royal Family as an interest to stay up to date on the latest Royal Family news, video, and analysis from ABC News.
And fans couldn't help but notice the number of times the mum-to-be touched and cradled her growing bump during the royal tour and beyond. "It'll be really special".