The MSP stood down as her party leader in August, saying feeling “hopelessly conflicted over Brexit” was one reason behind the move.
Ms Davidson, who backed remaining in the EU, clashed with Mr Johnson during the EU referendum and resigned her post a day after he announced plans to prorogue Parliament.
In a column for a national newspaper yesterday, she wrote: “The Prime Minister and I have had our issues in the past – some genuine, many more confected by excitable news coverage.
But Boris Johnson instinctively understands that you can’t move the country forward by re-running the referendums of the past.
“He is absolutely right to tell Nicola Sturgeon ‘no’, especially when the majority of people in Scotland don’t want another referendum in the near future.
“And he’s absolutely right to say, after more than three years of wrangling, that it’s time to Get Brexit Done.”
On independence she said Labour leader Jeremy Corbyn and First Minister Nicola Sturgeon “might be cooking up grubby backroom deals”, but she does not believe more referendums are the answer to “constitutional wrangling”.