The total meant that it was the busiest September on record for Denmark's capital city gateway.
"More passengers choosing to fly via Copenhagen rather than via Amsterdam, Frankfurt or London strengthens our position as the key hub of northern Europe," enthuses Thomas Woldbye, CEO of Copenhagen Airports.
"In September alone, 600,000 transfer passengers travelled via Copenhagen. That's an increase of 4.7%."
In September, traffic between Copenhagen and the six Polish destinations served from COP grew by 21%, or by 76,000 passengers.
The total means Poland overtook Greece to become the 15th most visited country by passengers flying out of the Danish capital.
Services from Copenhagen include SAS to Gdansk, Szczecin, Wroclaw and Poznan, SAS and LOT to Warsaw and SAS, Norwegian and Ryanair to Krakow.
"With six destinations in Poland and 507,000 passengers in 2019 so far, air traffic between Denmark and Poland has become quite dense," notes Woldbye.
"A total of 38% of the passengers on the six routes in and out of Poland transfer in Copenhagen. In other words, the Polish market has helped to strengthen Copenhagen Airport's position as a northern European hub," said Woldbye.
September's numbers mean that 23.3 million passengers used Copenhagen Airport in the first nine months of 2019 – a dip of just 17,000 on the same period last year.
"We may not have had traffic growth in the first nine months of the year, but that is mainly due to the bankruptcies of Primera Air and WOW, the strike among SAS pilots and Norwegian's new strategy of putting profitability ahead of traffic growth," explained Woldbye.
"When adjusted for these factors, we see a fine underlying traffic improvement."