The Duke and Duchess of Cambridge's royal wedding in 2011 was declared a public holiday by then Prime Minister David Cameron.
Royal fans are already speculating about the big day, including whether Prince George and Princess Charlotte will have roles.
However, a few grumpy sods took the time to let everyone know they really didn't care.
And enterprising wedding vendors got in quick to offer their services.
The UK's elite also took the opportunity to congratulate the couple.
Theresa May
British Prime Minister Theresa May offered her "very warmest congratulations", wishing the couple "great happiness for the future".
"I would like to offer my very warmest congratulations to HRH Prince Harry and Meghan Markle upon their engagement," said May.
"This is a time of huge celebration and excitement for two people in love and, on behalf of myself, the Government and the country, I wish them great happiness for the future."
David Cameron
May's predecessor David Cameron called the announcement "wonderful news", and wished the pair "a long and happy life together".
Archbishop of Canterbury
Justin Welby, the Archbishop of Canterbury, said he was "absolutely delighted to hear the news", wishing them "many years of love, happiness and fulfilment".
Israeli President Reuven Rivlin
The Israeli President, Reuven Rivlin, was the first world leader to publicly send his congratulations - going as far as to invite the happy couple to honeymoon in Israel.
Boris Johnson
Defence Secretary Boris Johnson wished the couple a long and happy life together, proclaiming the announcement "fantastic news".
Philip Hammond
Chancellor Philip Hammond wished the couple a "very happy future together".
