Sazerac chief executive Jake Wenz said Au had enjoyed a “phenomenal growth trajectory” since it was founded in Swansea.
“Au Vodka is a brand we’ve long admired,” he said.
“What Charlie, Jackson, and Charlie have achieved in just over a decade is spectacular and rare, and we have big plans for Au as we welcome the brand into the Sazerac family.”
He said that the deal would strengthen Sazerac’s position in the UK while creating “a path for continued global growth” for the vodka maker.
Au Vodka was founded by friends Charlie Morgan and Jackson Quinn, with broadcaster and DJ Charlie Sloth later joining as an investor.
Known for its distinctive bottles and cans, the company built a large following through social media marketing and celebrity collaborations.
It has grown into one of the UK’s best-known premium vodka brands, and employs more than 80 people in south Wales.