The company, which is part of Dawnfresh Seafoods, uses trout farmed on sites in Argyll to deliver products for retailers such as Marks & Spencer and Sainsbury.
The 170-strong team in Arbroath cures, smokes and slices the trout, producing around 170,000 packets of fish a week.
Dawnfresh employs more than 30 staff in farming fish, which is then sent for processing to Arbroath and Uddingston, Lanarkshire, as well as being exported abroad as whole fish.
The Princess was shown around the facility by Alastair Salvesen, chairman of Dawnfresh. During her visit, she witnessed how products were made, from the arrival of the ingredients to the finished product being despatched.
“High quality seafood is something for which Scotland is famous and our new unit processes fish grown at our sites in Argyll, some of which will end up on the plates of Her Majesty The Queen and her guests,” said Dawnfresh’s farming director Stewart Hawthorn.
“I am very proud that Dawnfresh gets to showcase its product around the world as well as to senior members of the Royal Family.”