In marked contrast to his brother, who remains firm that leaving the European Union without a deal would be no bad thing, and resigned because he believed the deal being negotiated was too soft, Mr. Jo Johnson called for a second referendum.
"On this most crucial of questions, I believe it is entirely right to go back to the people and ask them to confirm their decision to leave the European Union and, if they choose to do that, to give them the final say on whether we leave with the Prime Minister's deal or without it".
He already expressed fears that the current "chaotic" Withdrawal Agreement being finalised would be "a bad mistake" in a blog, published yesterday to coincide with his departure.
Cabinet ministers have been invited this week to read the UK's draft withdrawal deal with the EU.
Its leader Arlene Foster said Friday she could not vote for the deal if it could see the province treated differently from the rest of the UK.
He is the sixth minister in Theresa May's government to quit over Brexit.
Calling for a second referendum to be held on Brexit, Mr Johnson denounced the choice between Mrs May's deal plans or a no-deal scenario as a "failure of British statecraft on a scale unseen since the Suez crisis" that had left Britain facing "vassalage" or "chaos". My loyalty to the party is undimmed.
"My brother Boris.is as unhappy with the government's proposals as I am", he said. "But my duty to my constituents and our great nation has forced me to act".
"The referendum in 2016 was the biggest democratic exercise in this country's history".
"We've been hurtling towards a blindfolded Brexit for too long, so it's about time that politicians hand back control to the people of this country by giving them the final say on Brexit - with the option to stay and lead in Europe". We will not under any circumstances have a second referendum.
Pressed on whether more ministerial resignations were coming, Mr Johnson told Radio 4: 'It's for each MP to come to his or her own view.
He wrote: "Boundless admiration as ever for my brother Jo".
"Jo Johnson is the eighteenth minister to resign from Theresa May's government". While Johnson's resignation is likely to spur critics in the Conservative Party, securing a second referendum would also require support from the Labour Party, which is yet to fully clarify its stance on a referendum and what that could entail in terms of the question put to the public.