The company, which opened its first office in the British capital ten years ago, said the new site would allow its local workforce to reach 2,300 by the end of next year, a sign that it "is more committed than ever to the UK".
Chancellor Philip Hammond has hailed a new Facebook office as a "sign of confidence" in Britain.
It will open later today. The social network said more than half of the people working at the site in central London will focus on engineering, making it Facebook's biggest engineering hub outside the United States.
Facebook first arrived in London 10 years ago, and the new addition will take its total United Kingdom workforce up to 2,300 by the end of 2018.
London Mayor Sadiq Khan said Facebook's commitment showed the city is "at the forefront of global innovation".
It will also include an "incubator space" for start-ups, called LDN_LAB, which will help kick-start fledgling businesses.
"Today's announcements show that Facebook is more committed than ever to the United Kingdom and in supporting the growth of the country's innovative start-ups", said Nicola Mendelsohn, Facebook's vice-president for Europe, the Middle East and Africa. "This country has been a huge part of Facebook's story over the past decade".
The 247,000 sq ft building in Rathbone Place, off Oxford Street, designed by Frank Gehry, the architect, will house developers and sales staff. Services developed in the United Kingdom include Workplace, its office communication tool, and part of Facebook's Oculus virtual reality team. It announced the new headquarters previous year, shortly after Google said it was building a new hub in the city that will be able to accommodate more than 7,000 employees in total.
As well as engineers, there will also be developers, marketing and sales teams.
Extreme Fire Danger in SCV Through Thursday
Forecasters warned any fires that develop will spread rapidly, and recommended avoiding any activities that can spark a fire. And this one has the possibility of being extended for an additional one or two days into the weekend.
Enbridge Energy Sees Unusually Large Options Volume (EEP)
Narrowing in a bit closer, the 5 month price index is 0.94045, the 3 month is 0.98293, and the 1 month is now 0.97145. State Of New Jersey Common Pension Fund D holds 0.01% in Enbridge Energy Partners, L.P. (NYSE:EEP) or 88,900 shares.