Despite announcing a "war cabinet" to step up preparations for leaving the EU without a deal at the weekend, on his first visit to Scotland since becoming PM, today Mr Johnson also said he was "with Ruth" in his determination to avoid no deal Brexit, and to hammer out a new deal.
Ms Davidson, who did not support Mr Johnson in the Tory leadership campaign to replace Theresa May, has been clear that she cannot support a no-deal Brexit and said at the weekend: “I don’t think the government should pursue a no-deal Brexit and, if it comes to it, I won’t support it.”
She has also said is aiming to become Scotland's next First Minister at the 2021 Holyrood elections.
Today, while visiting the Faslane nuclear submarine base where he announced a new £300m growth deals package for Scotland, Wales and Northern Ireland, and ahead of a meeting in Edinburgh with Ms Davidson, Mr Johnson said he was "totally with Ruth in her political ambitions, I hope she succeeds here in Scotland and I will certainly do all I can to assist her."
He added: "I have a very good relationship with Ruth and I look forward to meeting her in a few hours.
"I'm with Ruth very much. She has been a fantastic leader of the Scottish Conservatives. I'm lost in admiration of what she has achieved - I'm a massive fan of the way she has taken the argument to those who would destroy our union and constitution and damage a global brand that is loved and admired and recognised around the world.
"I'm with Ruth in wanting to avoid a no deal Brexit. We are aiming for a new deal and that's what we can achieve with goodwill on all sides but it's been government policy for a while to prepare for no deal."
Mr Johnson, who will not be holding any public events in his visit to Scotland today, but will also meet with First Minister Nicola Sturgeon, said he was "not aiming for a no deal Brexit".
"What we want is to get a deal. I have had some interesting conversations with our European partners. I've talked to Jean Claude [Junker] and Angela Merkel and I'm reaching out today to Leo Varadkar and I've had a good conversation with Emmanuel Macron.
"The feeling is yes, there's no change in their position, but it's very positive and they all know where we are. We can't accept the backstop it's been thrown out three times, it won't work, and the Withdrawal Agreement as it stands is dead but there's ample scope to do a new and better deal and that's what Ruth and I want to achieve.
"I'm confident that we will get a deal, but it's also right that we prepare for no deal."
He added: "I don't aim for a no deal Brexit but clearly if we are going to make a success of the negotiations we have to prepare with a great deal of confidence and determination for a no deal outcome. We were in a high state of readiness on March 29 we will be in an even higher state of readiness come October 31. The more we prepare now the less chance of any disruption."
Asked about his poor personal poll ratings in Scotland, compared to England, Mr Johnson said if he "worried about polls he wouldn't be doing his job".
He added: "I think there is a campaign to destroy the union – it is represented by the Scottish Nationalist (sic) Party. I think that my ambitions to take the UK out of the EU... clearly they contradict the ambitions of the SNP and I think that their policies are entirely nonsensical.
"As far as I can make out they would literally want the population of Scotland to be using the Euro, to be handing back control of Scottish fish to the fisheries council in Brussels and I reject that... and I’m determined to campaign for the Union, in which I believe, north of south of the border."
However Mr Johnson's visit to Scotland does not include any public events - and his tour of HMS Victorious, one of the nuclear submarines based at Faslane, was conducted in private.
Asked why he had chosen to steer clear of the public, he said: "Ohhh .. nonsense! Who was there at Aberdeen Airport? Who was there at Aberdeen Airport [in May] where I met all sorts of... in a completely unhomogenised, unpasteurised, absolutely... I met all sorts of members of the public."
When it was pointed out to him that no reporters had been at Aberdeen as it was a private event, he added: "Ah right in that that case I’m very sorry. But you would have seen only wholly genuine and uncontrived non-Potemkin scenes, in which I was very warmly received by a hen party and many others.
"And look, you know, I think all this stuff is ever so, if I may say so respectfully, ever so slightly overdone. I’m here to represent the government of the United Kingdom, I believe passionately in the UK I think it’s the right thing for Scotland and I’m going to campaign for it north and south of the border."