British Prime Minister Theresa Mae said Thursday that London would need EU cooperation to ease any potential shocks that could occur if BRICCET was not reached.
Johnson has reiteratedly denied that Britain would have to leave the bloc by October 31 deadline, even if that meant withdrawal without agreement.
But avoiding border and business fluctuations would require EU support.
There is, of course, a very important element, reciprocity and cooperation, "Johnson told the BBC in an interview broadcast on Monday.
"The way we show our seriousness to our friends and partners will absolutely be by abandoning defeatism and negativity and preparation with confidence and seriousness" for the exit scenario without agreement.
Without the BRICCAST agreement between London and Brussels, Britain will automatically turn into a "third country" with the EU and trade between the two sides will follow WTO rules.
Johnson faces Foreign Minister Jeremy Hunt in a vote to choose the next British prime minister and take charge of London´s exit from the bloc.
Johnson, a former foreign secretary who served as mayor of London, was accused in the past of not having a detailed plan to remove Britain from the European Union.
Johnson said that the current May agreement to withdraw was "over" after the parliament rejected it three times.
But he believes there will be enough time to negotiate a new deal with the EU before the deadline and hopes the bloc will be ready to give London "time to apply" what is reached.
He said that if he wins, his government will not impose any effective controls or borders between Ireland, a member of the European Union and Northern Ireland of Britain, which was one of the most outstanding points during negotiations with the European Union.
