Johnson will start the visit Tuesday in The Gambia, where he will meet President Adama Barrow and visit the British-funded Medical Research Council, his ministry said.
Johnson's trip is a first since the country won independence from Britain in 1965. "I'm delighted to be the first foreign secretary to visit Gambia this week," Johnson said in a statement Monday.
Barrow, who worked as a supermarket security guard in Britain when he was younger, defeated long-standing hardline ruler Yahya Jammeh in polls in December.
He then took refuge in neighbouring Senegal after Jammeh refused to accept the election result and sought for weeks to cling to power.
The new leader was welcomed home by jubilant crowds in late January after Jammeh finally left the country.
The Gambia used to be part to the Commonwealth, a grouping of countries formerly ruled by Britain.
But Jammeh pulled the country out of the Commonwealth, calling it a "neo-colonial institution" and announced his intention to drop English as an official language.
Barrow has said he wants to rekindle ties with Britain.
"I am also very pleased that Gambia wants to rejoin the Commonwealth and we will ensure this happens in the coming months," Johnson said.
The British minister also hailed the December elections in The Gambia and Ghana, saying they "highlight the continuing strengthening of democracy in West Africa".
In Ghana, Johnson will meet President Nana Akufo-Addo and visit the Blue Skies company, a juice-maker which has received financial support from Britain.
Since being appointed last year, Johnson has been pursued by reminders of highly undiplomatic comments he made about different countries and world leaders while writing for the Daily Telegraph before he became a government minister.
'Watermelon smiles'
In a column published in 2002, Johnson mocked then prime minister Tony Blair's international travel in an article with the headline: "If Blair's so good at running the Congo, let him stay there".
He characterised the Commonwealth as having "crowds of flag-waving piccaninnies," using a derogatory term for black people that caused outrage.
He also parodied a Congolese reaction to Blair's arrival saying that "the tribal warriors will all break out in watermelon smiles to see the big white chief touch down".
The politically incorrect comments came back to haunt him when he ran for London mayor in 2008, and then again when he was named foreign secretary last year after Britain's shock Brexit vote, which brought down the government of premier David Cameron, his old Etonian schoolmate.
Johnson's colourful descriptions have not been limited to Africans.
He once compared the appearance of former US secretary of state and recently defeated White House candidate Hillary Clinton to that of "a sadistic nurse in a mental hospital".
Eyewitness? Submit your stories now via social or:
Email: news@pulselive.co.ke
