Three weeks ahead of its release, tickets to the value of more than £500,000 have been booked in advance, according to Walt Disney Pictures.
Odeon, the UK's largest cinema chain, said it had sold £245,205 in advance tickets, beating the record set by Harry Potter and The Goblet of Fire.
Rupert Gavin, chief executive of the Odeon cinema chain, called it a "phenomenal and record-breaking start" for the movie's UK run.
"Our cinemas have been inundated with calls to pre-book tickets for what could be the year's biggest kids and teen audience movie.
"With schools breaking up for half-term just as High School Musical 3 opens, we are bracing ourselves for a huge first week run," he added.
Odeon's advance ticket sales eclipsed the record set by the fourth Harry Potter film in 2005, which had taken £227,000 at the same stage of booking.
eta: more from jj
i like bbv's outfit but not tizz's.
the person posing with zac scares me!
1, 2, 3