The Baileys plant in Mallusk, County Antrim, has been awarded 'Diageo Plant of the Year for 2010' ahead of 70 other Diageo sites across the world.
The Mallusk plant was opened in 2003, and employs about 40 people.
It produces more than 60% of the world's supply of Baileys on one high-speed line, and exports it to over 130 countries.
Since the end of July, the plant has been working 24 hours a day in preparation for Christmas.
Plant manager Michael Hailes said the line is capable of turning out 24,000 bottles an hour, which is around half a million bottles a day, making it the fastest liqueur-filling line in the world.
"We source around 80% of our ingredients on the island of Ireland," Mr Hailes said.
"We buy milk from around 1,400 farmers to make the cream, and all our bottles are supplied by Quinn Glass in Derrylin.
"So we bring a lot of benefit to the economies on both sides of the border.
"To be named Diageo Plant of the Year is an outstanding achievement for the Mallusk operation, and testament to the outstanding teamwork and dedication of our staff."