Speaking to the Press Association, co-founder James Watt said the uncertainty has had a negative effect on British businesses.
He said the process will cause ‘severe long-term damage’ to the UK's economy and entrepreneurs.
‘Businesses need to know where they stand, need to know whether to invest, if they can build infrastructure, if they can employ people,’ he said. ‘The uncertainty is having such a negative effect on UK businesses.’
He added BrewDog's decision to buy the site of Stone Brewing in Berlin, which was announced earlier this month, was influenced by concerns over Brexit.
‘It's about having the ability to be able to supply our European customers given the political uncertainty,’ he said.
BrewDog revealed plans on Thursday to add a co-working space, beer-making experiences and a craft beer museum at the site, making it the company's flagship location in mainland Europe.
The company, which was set up in 2007 by Mr Watt and his school friend Martin Dickie, announced at its AGM this month that it is open for its sixth equity crowdfunding raise, targeting £7 million. Some of the money will be used to fund the refurbishment of the Berlin brewery.
It comes after BrewDog's latest accounts showed it swung to a loss before tax of almost £1.5m in 2018 due to high investment in opening new breweries and bars.