It is the first time any city has picked up the top prize eight times over consecutive years.
The annual Meetings and Incentive Travel poll is voted for by more than 3000 professionals.
GCMB chairman Gordon Matheson said: "Winning eight times is unprecedented but to become the first city to have done so over consecutive years is nothing short of remarkable and underpins exactly why we are now the UK's conference capital.
"The past eight years have been a huge success story for Glasgow and this award is the perfect springboard from which to ensure the next eight years and beyond are as equally successful.
"GCMB has confirmed business on the books through to 2021 and is bidding for new conventions business as far out as 2024."
Since the marketing bureau was set up in 2005, it has secured business tourism worth £1billion to the city's economy.
More than 2200 conferences have been brought to Glasgow, generating 3.3million bookings in city hotels.