Police said the last thing the man remembered was leaving a bar in Manchester city centre at 01:00 GMT.
He apparently woke up in a confused state before contacting Greater Manchester Police at about 15:00 GMT.
Thousands of people are expected to celebrate the festive season in what has come to be known as Mad Friday.
GMP tweeted about the man's nightclub ordeal, and said officers were searching for people with access to the building in order to free him.
A man dialled 999 after waking up locked in an empty nightclub dressed only in his underpants following a Christmas party.