Both airlines are already members of the oneworld alliance
Qatar's national airline has bought a near-10% stake in rival carrier, Cathay Pacific.
Qatar Airways has acquired approximately a 9.61% stake in Cathay Pacific Airways.
Both airlines already collaborate together as members of the oneworld alliance.
While Air China and Swire Pacific continue to hold 74.99% shares of the airline.
Qatar Airways already has a 20% investment in International Airlines Group (IAG) - the owner of Aer Lingus.
Commenting on the acquisition, Cathay Pacific CEO, Rupert Hogg said: "Qatar Airways is one of the world’s premier airlines.
"We already work together closely as fellow members of the oneworld alliance and we look forward to a continued constructive relationship."
Qatar Airways Group CEO, Akbar Al Baker added: "Qatar Airways is very pleased to complete its financial investment in Cathay Pacific."
"Cathay Pacific is a fellow oneworld member and is one of the strongest airlines in the world, respected throughout the industry and with massive potential for the future."
Qatar Airways flies daily from Dublin to over 150 destinations - while Cathay Pacific is to launch a direct year-round service between Dublin and Hong Kong from next June.