Liberty Global says the deal with Virgin Media means the company will have a total of 25 million customers in 14 countries.
It is already the largest cable operator in most of its 11 European markets. But the majority of revenue is expected to come from five countries - the UK, Germany, Belgium, Switzerland and the Netherlands.
Liberty Global says it plans to continue investing in Virgin's broadband network.
Virgin Media's new owner, Liberty Global, is controlled by John Malone who has been trying to seal a deal for more than a decade:
- Virgin Media was created by the merger of cable operators NTL, Telewest and Virgin Mobile in 2006
- Malone began buying up stock in Telewest and tried to acquire NTL back in 2000
- The deal marks his largest European acquisition
- Liberty Global already ranks as the largest cable operator in Europe with 18.4 million subscribers
A US cable firm has confirmed that it will buy Virgin Media in a deal worth $16 billion (£10 billion).
Liberty Global said the agreement would create "the world's leading broadband communications company".
With almost five million customers, Virgin Media is Britain's second biggest pay TV company, and Liberty Global is the largest cable operator in most of its 11 European markets.
Mike Fries, President and CEO of Liberty Global, said: "Virgin Media will add significant scale and a first-class management team in Europe's largest and most dynamic media and communications market."
Virgin Media CEO Neil Berkett added: "The combined company will be able to grow faster and deliver enhanced returns by capitalising on the exciting opportunities that the digital revolution presents, both in the UK and across Europe."
Sir Richard Branson's Virgin Group is to retain a 51% stake in Virgin Atlantic after Delta Air Lines agreed a deal to buy 49% of the airline.
Today's interim report shows just how important our calls were in the summer to find out what went on behind closed doors when deciding the future operator of the West Coast franchise and that it should be opened up to proper detailed scrutiny.
As well as the technical errors the review has identified, it raises fundamental questions around why more favourable treatment was given to one bidder over another and the lack of a clear and consistent account of how and what decisions were made.
All of this is a matter of serious concern and we hope these issues will be explored in greater detail in the final report by Sam Laidlaw.
Regardless of the catalogue of problems identified with the assessment process itself, we remain very clear that our own bid was robust and deliverable.
Lessons must be learned to prevent the process failures we saw with the West Coast competition from happening again and to protect the taxpayer and passengers from phoney bids that game the system.
In the short term passengers will need to be reassured by the Government that their day-to-day service won't be affected by the cancellation of the competition to run the West Coast franchise.
Longer term, the Government will need to work hard to restore confidence in the franchising process as these decisions affect millions of passengers on a daily basis.
Passengers will also want to know that the burden of costs arising from this cancelled process will not be directly passed on to them through hikes in fares.
Mr McLoughlin told MPs plans were continuing for an interim contract with Virgin to operate for up to 14 months while the franchise process was rerun.
He said passengers would see the same staff on the same trains and the service would be "enhanced":
In dealing with this, my department has been frank and open about its mistakes and is absolutely determined to find out exactly what happened.
Mr McLoughlin said the report made "uncomfortable reading" and outlined its findings.
He told the Commons:
It is clear that the inquiry has identified a number of issues which confirm that my decision to cancel the franchise competition was necessary.
These include a lack of transparency in the bidding process, the fact that published guidance was not complied with when bids were being processed, inconsistencies in the treatment of bidders and confirmation of technical flaws in the model used to calculate the amount of risk capital bidders were asked to provide to guard against the risk of default.
The Laidlaw inquiry also mentions factors "that appear to have caused or contributed to the issues raised".
Four Cabinet ministers have their fingerprints on the West Coast Mainline "franchise fiasco", Labour claimed in the Commons today.
Shadow transport secretary Maria Eagle said Transport Secretary Patrick McLoughlin, his predecessor and current International Development Secretary Justine Greening, Northern Ireland Secretary Theresa Villiers and Defence Secretary Philip Hammond have all played a role.
Do you agree ministers must take responsibility for serious or systematic performance failures, flawed policy and poor design?
Ministers must not be allowed to shuffle off responsibility - not my words but the words of the Prime Minister. This isn't just a faulty process, it's a faulty Government.
Patrick McLoughlin has read some of the interim findings from the Laidlaw report in to what went wrong with the West Coast mainline bidding process.
"In the limited time available this is necessarily only a preliminary report. What is clear however is that in seeking to run a complex and novel franchising competition process, an accumulation of significant errors, described in the report, resulted in a flawed process.
“These errors appear to have been caused by factors including inadequate planning and preparation, a complex organisational structure and a weak governance and quality assurance framework.
"The full causes and the lessons to be learnt will be addressed in the final report of my independent Inquiry to be published at the end of November.
“Firm judgements should not be made based upon what are provisional findings or wider conclusions drawn at this stage.”