The Princess was given a tour around some of the new facilities at the 300-year brewery in Dunbar which has received a £1m investment.
Belhaven Brewery Director George Howell showed The Princess some new equipment including a state-of-the-art mash conversion vessel, which processes malted barley. The investment will also help reduce energy costs.
Howell said: "It was a true honour to welcome The Princess Royal to our brewery and give her a guided tour of our new facilities.
"The technology Her Royal Highness was introduced to today will allow us to continue drawing on nearly 300 years of brewing experience at the same site that we began brewing from back in 1719. It will also help us maintain our position as one of the industry's leading players for many years to come."
The Princess Royal took the opportunity to catch up with brewery staff she first met on her previous visit to the brewery in 1988, including brew house operator John Smith, who has worked for Belhaven for more than 34 years.