The move, which is expected to be confirmed today in Hong Kong, makes the Gulf carrier the third-largest shareholder in Cathay.
Qatar Airways already has a 20% stake in British Airways owner International Airlines Group, 10% of LATAM Airlines Group and 49% of Italian airline Meridiana.
Hong Kong-based Cathay is currently undergoing a restructuring plan aimed at slashing HK$4 billion in costs over three years since posting its worst first-half loss in 20 years in August.
Qatar Airways group chief executive Akbar Al Baker said: “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.”
