The "sussexroyal" account, which so far has only one post featuring a monogram symbol with their names, was launched on Tuesday and now has 2.7 million followers.

The post alone garnered more than 960,000 likes for the Duke and Duchess of Sussex.

"We look forward to sharing the work that drives us, the causes we support, important announcements and the opportunity to shine a light on key issues," the couple said in their post.

The couple are expecting their first baby in the coming weeks.

Read also: UK's Prince Harry and Meghan launch their own Instagram account

The royals beat a record previously held by South Korean K-pop singer Kang Daniel, who achieved one million followers in 11 hours, 36 minutes.

The record before him was held by Pope Francis, who reached the million mark in 12 hours after launching his channel "franciscus" in 2016.

Meghan, a former actress who starred in the hit US television show Suits, deleted all her personal social media accounts ahead of her wedding to Harry in May 2018.

Harry took part in a ballet class four youngsters on a visit to west London on Wednesday.