Boyega posted a clip on Instagram of the moment he entered the screening after being introduced, teasing that there would be more to come, reported Digital Spy.
He wrote: "Surprising London fans! 02 Greenwich takeover! Onto the next movie theatre."
He later posted two clips of himself surprising a family watching the "Star Wars" trailer.
"The Force Awakens" has smashed the record for the highest opening weekend ever, taking in USD 238 million and beating the previous record holder Jurassic World.