The alarm was triggered at 12.40pm today (Monday).
There were no planned fire drills and passengers were evacuated from the building.
The terminal building has now reopened and an LBA spokesperson confirmed the airport is investigating the issue.
Several flights were delayed to give passengers time to board - but the airport said no passengers missed their flights.
A spokesperson for LBA said: “LBA was evacuated early this afternoon due to an unplanned fire alarm.
"We are investigating the cause of the alarm. LBA staff returned the terminal to normal operations rapidly after the incident and no passengers missed their flights due to the alarm.”
It comes as airports across the UK face travel chaos following staff shortages.
With many staff having been let go at the height of the pandemic, airports have struggled to cope as passenger numbers return to pre-pandemic levels.
The CEO of Leeds Bradford Airport previously issued an apology to all customers impacted by 'current queuing issues'.
"I’m sorry for all passengers that have had a negative experience travelling at LBA in recent weeks and want to assure everybody across the region that we have solutions in place to fix these problems as quickly as possible," said, CEO, Vincent Hodder.
"We’re doing everything we can to make travelling through LBA is as smooth and comfortable an experience as possible, whilst also being a safe environment."
The airport continues to advise passengers to arrive at the airport and join the security queue at the time advised by their airline, but no earlier than three hours before their flight.