Johnson arrived in New York on Sunday where he held meetings with Steve Bannon, Trump's chief strategist, and Jared Kushner, the President-elect's son-in-law and close adviser during the transition, a UK Foreign Office official confirmed.
He will not meet with Rex Tillerson -- the nominee for US Secretary of State -- as the protocol is to wait until after the confirmation process,
which is due to begin later this week.
Johnson, a former mayor of London, was given his current position following the narrow success of 2016's referendum to leave the European Union, commonly referred to as Brexit. A former journalist and television personality, he was the highest profile supporter of the "Leave" campaign.
He is the UK's first Foreign Secretary to also be an American citizen. He was born in New York, and holds dual citizenship.
In 2014, Johnson acknowledged he was disputing a demand for capital gains tax
from the US tax authorities, which ultimately he paid. In February 2015, he announced his intention to give up US citizenship
to prove his loyalty to the UK, but so far there has been no indication he has done so.
Johnson, a member of the UK's ruling Conservative Party, has been critical of Trump in the past.
Responding to the President-elect's comments in 2015
that parts of London are "so radicalized that the police are afraid for their own lives," Johnson said
: "The only reason I wouldn't go to some parts of New York is the real risk of meeting Donald Trump."
The US trip also follows a remark from UK Prime Minister Theresa May to Sky News
that Trump's comments about groping women were "unacceptable." However she voiced hopes that the relationship between the two countries could flourish during his presidency.
Johnson may find Trump's team more in line with his views and style than that of President Barack Obama. The foreign secretary's statements about the current administration made for at least one awkward public encounter when he held a joint press conference with his US counterpart
, Secretary of State John Kerry. Although Johnson has knocked Trump in the past, he has also defended him from criticism in Europe.
After his victory in the presidential election, Trump took the unorthodox step of suggesting the pro-Brexit politician Nigel Farage be named the UK's envoy to the US. May declined to extend
the position to Farage.
Trump confirmed earlier this weekend that May, who ascended to the country's highest democratic office following the resignation of Prime Minister David Cameron in the wake of the Brexit vote, would visit him in the coming spring.
"I look very much forward to meeting Prime Minister Theresa May in Washington in the Spring. Britain, a longtime US ally, is very special!" Trump tweeted.