The direct service will operate four times a week
The inaugural non-stop flight between Dublin and Hong Kong took off from the capital earlier.
The Cathay Pacific service is carrying a full complement of 280 passengers.
Flight CX306 is an Airbus A350-900 aircraft with the registration B-LRI.
The route is the airline’s third new European service in 2018, following direct flights from Brussels and Copenhagen in March and May.
The Hong Kong-based airline currently operates to 15 destinations in Europe.
Cathay Pacific general manager for Europe, James Ginns, said: "We're delighted that Ireland’s first and only non-stop flight to Hong Kong has been well-received by our customers.
"Our team is thrilled to be able have a role in fostering bilateral tourism and economic growth between Ireland and Asia.
"We feel confident that this new route will continue to bring more convenience and choice to the Irish public and optimise opportunities for Irish businesses."
The flight has special meaning for its commander, Senior Captain Ian McGuinness, who said: "I'm happy to be able to operate this very first service between my between my home town of Ireland and my adopted city of Hong Kong.
"I grew up in Ireland and have lived in Hong Kong for the past 17 years.
"Both places are vibrant and dynamic, and I'm pleased that customers can now enjoy a direct link to explore the beauty and culture of my abodes that I have grown to know and love."
.@DublinAirport Managing Director Vincent Harrison said 'today is a historic & momentous occasion for Dublin Airport & Ireland' @cathaypacificUK route launch #DUBHongKong #Connectivity #New Routes pic.twitter.com/F5xCjOwwj3— Dublin Airport (@DublinAirport) June 2, 2018
Departing passengers enjoyed a special gate ceremony to celebrate the launch on Saturday morning - with refreshments and a traditional Chinese lion dance performance.
They also received a personalised flight certificate to commemorate the first flight, as well as a gift pack.
Dublin Airport managing director Vincent Harrison said this is a momentous day.
"We are delighted to welcome Cathay Pacific to Dublin Airport and to Ireland.
"Today is the result of collaboration of many years work with a wide range of other bodies such as Irish Embassy in China, the Consulate in Hong Kong, our colleagues at Tourism Ireland and other key stakeholders such as IDA Ireland, Enterprise Ireland and Bord Bia."
Trade between Ireland and China is worth more than €8bn per year, and almost 100 Irish firms have operations in China - employing a total of 100,000 people there.
There are an estimated 4,000 Irish people living in Hong Kong and about 40,000 people per year travelling between the two cities.
The direct service operates on a four-times-weekly basis - departing Dublin every Monday, Wednesday, Thursday and Saturday - and arriving in Hong Kong at 7.00am the next day.