Carrie Johnson held baby Romy in her arms as she gave her support to her husband Boris Johnson during his resignation speech outside No10.
It marks the first time Romy’s face has been seen in public, with pictures previously being taken from behind.
Mrs Johnson and their seven-month-old daughter joined the Tory leader’s close aides to offer moral support as he stood at the podium in Downing Street.
The 34-year-old former Conservative Party media official – who also shares two-year-old son Wilfred with the politician – flashed a supportive smile from the crowd.
For the occasion, she wore a statement £325 red dress from LK Bennett.
In his address, Mr Johnson acknowledged the sacrifices his wife has had to make during his time in office.
He said: “I want to thank Carrie and my children and all my family, who have put up with so much for so long.”
Mr Johnson expressed his regret at having to step down, saying how “sad” he was “to be giving up the best job in the world – but them’s the breaks”.
He said: “It is clearly now the will of the parliamentary Conservative Party that there should be a new leader of that party and therefore a new prime minister.
“And I’ve agreed with Sir Graham Brady, the chairman of our backbench MPs, that the process of choosing that new leader should begin now and the timetable will be announced next week.
“And I’ve today appointed a Cabinet to serve, as I will, until a new leader is in place.”
Since Tuesday 59 members of his government have left as anger mounted over his handling of the Chris Pincher groping allegations.
Mr Johnson was determined to fight to stay in office but he failed to persuade his Cabinet colleagues otherwise and consequently he has handed in his resignation.
He will stay in office while the race to appoint the new leader is underway.
