Appearing outside the door to No.10 on Tuesday, Mr Johnson promised “the most fervent support” to his successor Liz Truss as he prepares to step aside.
But in doing so, he also appeared to hint at his plans for the future as he compared himself to Roman statesman Cincinnatus.
In his farewell speech, he said: “On the subject of bouncing around in future careers, let me say that I am now like one of those booster rockets that has fulfilled its function.
“I will now be gently re-entering the atmosphere and splashing down invisibly in some remote and obscure corner of the Pacific.
“Like Cincinnatus, I am returning to my plough and I will be offering this Government nothing but the most fervent support.”
Cincinnatus and Boris Johnson
Wiki Commons/PA
Boris Johnson with his wife, Carrie, outside No.10
Yui Mok
Cincinnatus was a Roman statesman who became a legendary figure of virtue by the time of the late Republic, before his death in 430 BC.
An invasion is said to have prompted his fellow citizens to call for his leadership and he "came from his plough" to assume control of the state.
After achieving a decisive 16-day victory, he relinquished power and returned to his farm.
His success and immediate resignation has often been cited as an example of outstanding leadership.
But perhaps more importantly in the context of Mr Johnson, Cincinnatus was called back to power by patricians to suppress an uprising of plebeians under Spurius Maelius.
He then ruled for a second time as Roman dictator, after which he is said to have ceded power once again.
Earlier in his speech on Tuesday, Mr Johnson said: “This is it, folks.
"Thank you everybody for coming out so early this morning. In only a couple of hours I will be in Balmoral to see Her Majesty the Queen and the torch will finally be passed to a new Conservative leader.
“The baton will be handed over in what has unexpectedly turned out to be a relay race. They changed the rules halfway through, but never mind that now.”
Boris Johnson addresses the media outside Downing Street
Stefan Rousseau
Mr Johnson's speech was met with enthusiastic applause
Victoria Jones
Mr Johnson held his wife’s hand and shook hands with officials as he left the street to rapturous applause.
He will travel to Balmoral later on Tuesday, to formally tender his resignation to the Queen.
Ms Truss will take over from Mr Johnson on Tuesday afternoon, and she will also make the trip to the Queen's Highlands home.
The Queen has opted not to travel back to London for the customary Buckingham Palace address with the Prime Minister in waiting.
Her Majesty will hold an audience with the new Tory leader, where Ms Truss will be invited to form a government and take over as PM.