Boris Johnson and Carrie Symonds have named their baby boy Wilfred Lawrie Nicholas Johnson, she has announced on Instagram.
The new mum also shared the first pic of the tot and explained why they had chosen the names.
The Prime Minister and his fiancée welcomed the baby at a London hospital on April 29.
A statement from the couple's spokesman said they welcomed a "healthy baby boy at a London hospital earlier this morning".
Their spokesman added that "both mother and baby are doing very well".
When did they reveal their pregnancy?
Reports emerged in February confirming Boris and Carrie were expecting their first baby in 'early summer'.
The couple also confirmed their engagement.
What did they say?
A source for Downing Street said: "Boris and Carrie are both delighted at this news.
"They have both known for a while but have kept it under wraps until the pregnancy progressed.
"It partly explains why he has been lying low recently - although he works flat out and that won’t change."
Boris has four children with his estranged second wife Marina Wheeler, and a love child from an affair with property developer Helen Macintyre.
Boris' coronavirus scare
Last month, Boris was admitted to hospital after testing positive for coronavirus.
A short time later, his condition worsened and doctors put him in intensive care.
After three nights in intensive care, doctors eventually moved him to a standard ward.
Meanwhile, Carrie revealed she had also experienced symptoms.
She said on Twitter earlier this month: "I’ve spent the past week in bed with the main symptoms of coronavirus.
"I haven’t needed to be tested and, after seven days of rest, I feel stronger and I’m on the mend.
"Being pregnant with COVID-19 is obviously worrying."
The prime minister is now back to work after recovering from the deadly bug.
He recently made a speech and urged Brits to continue following lockdown rules.
Leave us a comment on our Facebook page @EntertainmentDailyFix and let us know what you think of this story.