In a sign of the difficulty Mr Johnson may face in building bridges with opposite numbers around the world, French foreign minister Jean-Marc Ayrault told Europe 1 radio: "I am not at all anxious about Boris Johnson, but you know his style, his method during the campaign".
"There is a massive difference between leaving the European Union and our relations with Europe, which if anything I think are going to be intensified and built up at an intergovernmental level".
"After a vote like the referendum result on Jun 23, it's inevitable that there is going to be a certain amount of plaster coming off the ceilings in the chancelleries of Europe", he said.
On Monday, Johnson is expected to sit down in a formal day-long meeting with his EU peers, with issues on the agenda ranging from EU-China ties to migration policy in Africa.
In April, Johnson suggested that U.S. President Barack Obama had an "ancestral dislike" of Britain because he is part-Kenyan.
When asked about how the role of Foreign Secretary might change after the creation of these new appointments, Mr Johnson said: "We will be working very closely, as you can imagine, with the new departments for worldwide trade and for the withdrawal from the EU".
Mr Johnson's drawing of parallels between the EU's aims for a united Europe and that of Hitler has not been forgotten in European capitals.
"He told a lot of lies to the British people and now it is him who has his back against the wall". Foreign Minister Frank-Walter Steinmeier's initial reaction was worthy of Boris: He mocked Johnson for having skipped out on his duties to lead Britain after the Brexit vote and having "instead played cricket", which he called "outrageous".
The Cabinet of Britain's new Prime Minister Theresa May will be tasked with negotiating the country's withdrawal from the European Union.
Four EU and British sources told Reuters on Thursday it was unclear the dinner would go ahead and if so, who among Johnson and the 27 other EU ministers would attend.
"I need a partner with whom I can negotiate and who is clear, credible and reliable", he added.
Britain's Foreign Secretary Boris Johnson addresses staff inside the Foreign Office in London.
The figure did not take account of London's budget rebate or of European Union spending on public and private sector projects in the United Kingdom, and Leave campaigners have since acknowledged it was inflated. German Finance Minister Wolfgang Schaeuble said Thursday: "We must let Her Majesty's new government have a bit of time to make the necessary decisions". He angered and frustrated many Britons who voted to remain, along with other European leaders who believe Britain made a great mistake.
One might divide the world into West and East-Lord knows Boris would-in terms of reaction.
May's decision to appoint the eccentric Johnson as Britain's top diplomat raised eyebrows around the world as he is known for his distinctly undiplomatic gaffes about a host of foreign leaders.
Some of former prime minister David Cameron's Cabinet ministers kept their portfolios, including Defense Secretary Michael Fallon, but most ministries were shuffled, with new ministers including Justice Secretary Liz Truss and Education Secretary Justine Greening.