The Gambian government withdrew in 2013 under its then leader Yahya Jammeh, who called it a “neo-colonial institution”.
But Adama Barrow, who was sworn in as president in January, lived in Britain for three years when he was younger and has said he wants to rekindle ties.
Foreign Secretary Boris Johnson is to visit the West African nation on Tuesday, where he will meet Mr Barrow and visit the British-funded Medical Research Council.
Mr Johnson said he was “delighted” to be the first British foreign secretary to visit The Gambia since the country won its independence from Britain in 1965.
“I am also very pleased that Gambia wants to rejoin the Commonwealth and we will ensure this happens in the coming months,” he added.
Mr Barrow’s path to the presidency was not smooth.
He had been a political unknown but was thrust into the limelight when eight opposition parties put him forward as a unifying figure.
The former Argos security guard defeated hardline ruler Yahya Jammeh in December, but Mr Jammeh clung to power, saying there had been irregularities in the election.
Troops from other West African countries prepared to cross the border to force him to cede power and Britons in the country were warned to get outamid safety concerns.
After a lengthy stalemate, Mr Jammeh finally went into exile and Mr Barrow returned from Senegal, where he had taken refuge.
Mr Jammeh, who had been in power for 22 years, has been accused of emptying the country’s banks of 500m Gambian dalasis (£9.2m) in the last two weeks of his reign.