Google's $12.5bn (£7.9bn) purchase of US phone maker Motorola Mobility has been completed days after it received approval from the Chinese government.
Chinese authorities said Google must keep its mobile software, Android, free for other device makers for up to five years.
The acquisition is Google's biggest to date.
The internet search giant has also named a new management team for the phone handset maker.
Motorola is a leading manufacturer of smartphones and other devices.
Google's takeover of the business allows it to move into the manufacturing of phones and tablet computers for the first time.
Google's chief executive, Larry Page, said in a blog post that there were people using devices now who may never use a desktop machine: "The phones in our pockets have become supercomputers that are changing the way we live. It's now possible to do things we used to think were magic, or only possible on Star Trek- like get directions right from where we are standing; watch a video on YouTube; or take a picture and share the moment instantly with friends."
He added that Motorola had a long history in technological development: "Motorola is a great American tech company that has driven the mobile revolution, with a track record of over 80 years of innovation, including the creation of the first cell phone."
He said he saw the new business producing "the next generation of mobile devices that will improve lives for years to come".
The purchase gives Google access to more than 17,000 of the company's valuable patents.
The Chinese authorities cleared the deal on condition that Google keeps its mobile software, Android, free for other device makers for up to five years.
The European Commission also approved the deal, but it did not conclude there was an issue with Android, saying it was unlikely that Google would restrict the use of Android solely to Motorola, which is a minor player in the European Economic Area.
US approval has also been granted.