The Twitter hashtag #Brexit topped the list of trending topics. Nigel Farage, a key player in the "Leave" movement, declared the U.K. had its "Independence Day."
Some drew parallels to the populist nature of the Brexit campaign and the looming U.S. presidential election.
Others made jokes — some darker than others.
David Rothkopf, CEO and editor of FP Group, which publishes Foreign Policy magazine, referenced the plummeting of the British pound.
The official Twitter account for the popular political drama "House of Cards" posted a gif of the show's devious protagonist, Frank Underwood.
Others expressed dismay.
Former Oasis singer Liam Gallagher also weighed in Friday morning.
PHOTOS: See more Brexit reactions below