Ms Markle praised the group, saying the diversity of the women was "pretty outstanding" with 12 countries represented.
Meghan says she felt "embraced" by the women from the community kitchen after just moving to London.
Duchess Meghan joined some women from the Hubb Community Kitchen to cook a meal of coconut chicken curry, aubergine masala and chapatis for the invited guests.
Meghan looked incredible as she showed off her elegant, yet eye-catching, sense of style at the book's launch event in London, as she stepped out in a sophisticated pleated black skirt, paired with a simple black sleeveless top.
Meghan helped put the group in touch with a publisher and her Royal Foundation provided assistance with legal and administrative issues.
Her mother Doria Ragland was also on hand to support her daughter's first royal solo project.
In a speech to guests, she said the project had been a "tremendous labour of love".
Her mum, meanwhile, embraced each of the women with a warm hug, telling them: "It's fantastic".
"And when you know the story of the recipe, you get to know the person behind it, and that's what we're talking about in terms of coming together to really engage and talk and to be able to really celebrate what connects us rather than what divides us". "I'm so excited to see the projects you're going to continue doing in your own community, the community at large, and also how you're going to inspire people globally by sharing your stories and recipes". Speaking of the duchess's experience at the kitchen, she said: "She felt very much at home".
In the new book supported by Meghan, some of the recipes are family favourites and all have been created by the cooks who support not only residents affected by the Grenfell fire but others in the community. It's already number one on Amazon.
In it, Meghan wrote that the Hubb - which means love in Arabic - "is a place for women to laugh, grieve, cry and cook together".
The book was inspired by Markle's visit to the Hubb Community Kitchen in North Kensington, which could only open a few days a week for lack of funds.
She phoned their mother, who was with them on the 19th floor to warn them about the fire - giving them enough time to get out of the building.