In a post on the couple's Instagram account, Harry expressed his excitement about the much anticipated trip as well as highlighting organisations "working towards positive change".
Harry said: "In just a few weeks our family will be taking its first official tour to Africa, a region of the world that over the past two decades has been a second home to me.
"Our team has helped create a meaningful programme that we're so excited to share with you. On a personal note, I can't wait to introduce my wife and son to South Africa! We'll see all of you very soon."
The caption continued: "Our monthly social awareness approach follows key accounts that inspire us and highlight those working towards positive change.
"As a lead up to the tour, for the month of September, we wish to celebrate the beauty of this wonderful continent as a whole: from local organisations working hard to better the environment, to the young leaders paving the way for a better future for the Commonwealth and beyond.
"These selected groups are a small representation of the incredible work being done in Africa today from countless people, local communities and organisations."
The couple have asked people to consider following or supporting more than 20 Instagram accounts including Sentebale, which was founded by Harry and Prince Seeiso.
Baby Archie will be around five months old when his parents take him on his first official overseas trip.
Harry and Meghan both share a passion for Africa and are said to be looking forward to deepening their knowledge of the continent's rich culture and history.
The couple also admire South Africa's former president Nelson Mandela and they have already met members of his family in the UK and could meet them again in their home country.
Botswana is a place Harry loves and knows well, and he reportedly whisked his wife to the southern African country in 2017 to mark her 36th birthday - a year after their love blossomed during a brief visit soon after they met on a blind date.
Speaking during their engagement interview, Harry said: "I managed to persuade her to come and join me in Botswana.
"And we - we camped out with each other under the stars... she came and joined me for five days out there, which was absolutely fantastic."
The duke's charity Sentebale has recently expanded its work into Malawi and Harry could see the latest developments and its work in Botswana, helping young people living with HIV and Aids.
The charity was founded in Lesotho, a landlocked country within South Africa.
The duke also has a passion for African wildlife and is president of African Parks, patron of Rhino Conservation Botswana and spent part of his summer in 2016 working on conservation projects in Africa.