Was the wedding a surprise in Westminster? Political Correspondent Daniel Hewitt reports
The couple exchanged vows in Westminster Cathedral in front of a small group of close friends and family.
Downing Street confirmed that Boris Johnson and Carrie Symonds married on Saturday May 29.
The pair will have a larger celebration in 2022, at a time when coronavirus restrictions are likely to have been relaxed.
A Number 10 spokesman said on Sunday: “The Prime Minister and Ms Symonds were married yesterday afternoon in a small ceremony at Westminster Cathedral. “The couple will celebrate their wedding with family and friends next summer.”
According to the Sun, even senior Downing Street aides were unaware the couple had tied the knot.
Just days ago, the couple were said to have sent save-the-date cards to family and friends for an event on July 30, 2022.
The couple announced their engagement and news that they were expecting their first child in February last year.
Mr Johnson and Ms Symond's son, Wilfred was born two months after the announcement.
The marriage will be Mr Johnson's third after he finalised his divorce from his second wife Marina Wheeler in 2020.
The wedding ceremony was reportedly carried out at the Catholic cathedral by Father Daniel Humphreys. The priest had baptised Wilfred last year.
Shortly after 1.30pm, the church was suddenly cleared of visitors, with staff saying it was going into lockdown, the Sun reported.
Half an hour later, a limousine carrying the bride arrived at the piazza outside the main west door. Ms Symonds wore a long white dress but not a veil, The Sun said.
Mr Johnson’s father, Stanley, was spotted in Downing Street after the ceremony, while guests and musicians were seen leaving No 10 following the reception.
A picture posted on Twitter by Foreign Office minister James Cleverly showed a barefooted Mrs Johnson with her new husband who had discarded his jacket and tie.
Decorations were hanging from trees and a drinks table had been fashioned from bales of straw.
Under current coronavirus rules, weddings in England are only allowed with up to 30 people in Covid-secure venues.
Dancing is not advised, although there is nothing advising against the couple’s traditional first dance.
Chancellor Rishi Sunak tweeted on Sunday afternoon: "Congratulations to my friends and neighbours @BorisJohnson and @carriesymonds on their wedding yesterday!"
Cop26 President Alok Sharma sent “love, hugs and all best wishes”.
Culture minister Caroline Dinenage said the new Mrs Johnson “looks adorable”, while Health Secretary Matt Hancock offered the couple “best wishes on a happy future together”.
Northern Ireland’s First Minister Arlene Foster tweeted: “Huge congratulations to Boris Johnson & Carrie Symonds on your wedding today.”
But Labour former frontbencher Jon Trickett said the wedding was “a good way to bury this week’s bad news” on former advisor Dominic Cummings’ testimony, the spread of the Indian coronavirus variant and the controversy over how the Downing Street flat refurbishment was funded.
Mr Cummings, who was Mr Johnson's former aide, claims Ms Symonds had been desperate to oust him from his role and had sought to put her own friends in key positions.
He also claimed that in February 2020, when the Covid-19 outbreak was becoming a major global crisis, Mr Johnson was “distracted by finalising his divorce, his girlfriend wanted to announce being pregnant and an engagement, and his finances”.
Fellow Labour MP Tonia Antoniazzi suggested the “emergency marriage plan” was an attempt to “deflect from negative press” from Mr Cummings.
She tweeted: “They know he won’t be able to plan one in Chequers cos he won’t be PM next year…”
Christopher Goodyear, a witness protection officer in the Metropolitan Police homicide division, said: “He’s now married in the Catholic church so he can’t get married again – if he does then that invalidates everything.
“So let’s hope he keeps his trousers on and behaves himself.”
Why was the twice-divorced PM allowed to marry in the Catholic church? The Prime Minister may never have been previously married in the eyes of the Catholic church, an expert has said. As neither his six-year first marriage to Allegra Mostyn-Owen, nor his second 27-year marriage to Marina Wheeler were Catholic ceremonies, in the eyes of the church they may be invalid. Matt Chinery, an ecclesiastical and canon lawyer, told Times Radio on Sunday: “There is a requirement if you are a Roman Catholic that you must have your wedding overseen by a Roman Catholic priest or deacon.” He explained that any other form of marriage “is not valid unless you had previous permission from your bishop to marry outside of the Catholic church”.
Boris Johnson was baptised as a Catholic, but was confirmed as an Anglican as a teenager. Mr Chinery explained: “What I think has happened here is that the Catholic church has looked at Boris Johnson’s first two marriages (and) seen that he’s a Roman Catholic by baptism. “They’ve looked at that, said ‘you are a Catholic because you were baptised Catholic, your first two weddings weren’t in a Catholic church overseen by a Catholic minister therefore the Roman Catholic church does not recognise those two marriages as valid’.” He added: “So in the eyes of the Catholic church Boris Johnson woke up last week as somebody who wasn’t married and had never been married and so was free to marry in the cathedral this weekend.”