Their record was only beaten by Jennifer Aniston, who reached a million followers in five hours and 45 minutes, when she finally took the plunge and joined the site in October.
Despite reaching the 10M mark, Harry and Meghan still trail behind the Duke and Duchess of Cambridge, whose Kensington Royal account has 10.6 million fans.
Aside from the young royals’ impressive figures, Her Majesty’s account, The Royal Family has garnered 7.1 million followers, while Charles and Camilla’s Clarence House account has 939K followers.
While many images proved to be popular with fans, the most “liked” snap on the Sussex Royal Instagram account was unsurprisingly a pic of little baby Archie.
The black and white photo, which was taken when Harry and Meghan introduced Archie to the Queen and Prince Philip, alongside grandmother Doria Ragland, reached 3M “likes”.
Harry and Meghan’s impressive feat comes after it was rumoured they could be set to launch their very own magazine or newspaper under their Sussex Royal brand.
Last June, the royal couple submitted an application to trademark hundreds of products and services under their banner – including a newspaper and a magazine, Express reported.
The royal couple’s application to trademark the items came just days after they announced they had split from Prince William and Kate Middleton’s charity, The Royal Foundation.
Kensington Palace issued a statement at the time that revealed The Royal Foundation will be the “principal charitable and philanthropic vehicle for The Duke and Duchess of Cambridge”.