The blaze occurred just before 10 a.m. at The Pier, the carrier's largest premium facility at Hong Kong International Airport, which serves thousands of travelers daily, according to the South China Morning Post.
Staff immediately alerted emergency services, and firefighters extinguished the fire within an hour, with no injuries reported, RTHK News said.
Authorities stated that smoke was detected coming from an electrical meter room at the lounge.
An investigation into the cause of the fire is ongoing.
Cathay Pacific apologized for the inconvenience caused to its customers in a statement.
A police spokesman said, as cited by SCMP, that an initial investigation "points to a short circuit as the cause, which is not considered suspicious."
By Sunday, the carrier announced that the lounge had reopened after a day of closure for repairs.