The Office of Fair Trading has given Facebook's takeover bid for Instagram the green light after deciding not to refer it to the Competition Commission.
The decision brings Facebook a step closer to acquiring the photo-sharing phenomenon.
In April, a month before going public, the company had announced it was buying Instagram for $1bn (£637m).
The OFT had been investigating whether the merger would restrict people from using other apps or other sites.
There were concerns that the takeover would prevent people from uploading pictures from Instagram to sites other than Facebook or other apps' ability to upload to it.
Since its launch in 2010, Instagram has won more than 50 million users, and nearly half of the world's top brands use it as part of their marketing strategy, according to a recent study.
Facebook has lost some of its lustre since its May flotation and after reporting a $157m loss in the second quarter, although most of it was due to pay-outs to the company's early investors, including chief executive Mark Zuckerberg.
There are concerns over whether Facebook can make money from people using the site on mobile devices, as users move from the computer desktop version to accessing the site via mobile phone.
The company is now making less money from each user as it becomes more difficult to generate advertising revenue.