The deal, which has been in the works at least since January, continues a trend of consolidation among European service providers. Hutchison already owns Three, one of the U.K.'s biggest carriers. Together, Three and O2 would form the country's number one mobile operator by subscribers, according to news reports.
O2 is currently owned by Spanish multinational mobile giant Telefónica. Hutchison agreed to make an initial payment of 9,250 British pounds (about $13.7 billion) when the deal closes and pay another 1 billion pounds when cash flow from the combined company reaches a certain level, Telefónica said. The total price would exceed $15.2 billion, based on Tuesday's exchange rates.
The transaction still needs regulatory approvals. It would cut the number of major mobile operators in the country from four to three.
Hutchison, based in Hong Kong, owns mobile operators under the Three name in several countries across Asia and Europe. It also has interests in property, ports, retail, energy and infrastructure.
The O2 buyout is the second big mobile deal in the U.K. this year. Last month, BT agreed to buy mobile carrier EE from Deutsche Telekom and Orange for about $19 billion.
Stephen Lawson covers mobile, storage and networking technologies for The IDG News Service. Follow Stephen on Twitter at @sdlawsonmedia. Stephen's e-mail address is stephen_lawson@idg.com