This is despite the Cambridges' account 'Kensington Royal' being around for much longer, while the Sussexes only started their account last April.
Prince Harry, 35, and Meghan Markle, 38, who run Sussex Royal, have seen their following skyrocket since announcing their retreat from public life last week, Mail Online reported.
The couple, who will split time between Canada and Windsor Castle after they stepped down as senior royals, have now overtaken Kensington Royal, run by Prince William, 37, and Kate Middleton, 38, for some time.
While Kate and William have shared 1,982 posts, Harry and Meghan have only posted 185 times since last April.
The Kensington Royal account gets an average of 300,000 likes for their posts, with statement posts, including Kate Middleton's birthday racking up 1.2 million likes.
Meanwhile Sussex Royal gets a similar average, but their recent post announcing they would be stepping down garnered almost 2 million likes from supportive fans.
While William and Kate's account follows just under 100 people, Harry and Meghan follow new accounts each month to highlight charitable causes.
On January 19, the Duke of Sussex said he is "taking a leap of faith" in stepping back from his life as a member of the royal family, but "there really was no other option".
Harry gave an emotional speech, where he told the "truth" about leaving royal duties behind in a bid for a "more peaceful life" for his family.
( With inputs from IANS )