Clegg lost his seat in his student-heavy constituency of Sheffield Hallam in the 2017 United Kingdom general election, having held it since 2005 when he succeeded fellow Lib Dem Richard Allan - who also happens to work at Facebook, as director of policy in Europe. "I hope I will be able to play a role in helping to navigate that journey".
He'll replace Elliot Schrage, who recently announced he would be leaving after a decade at the tech giant.
Mr Clegg, a strong advocate of Britain's membership of the European Union, said it was a "wrench" to be leaving the public debate at a crucial time in Brexit, but added that key decisions would pass to parliament, of which he was no longer a member.
He will start work on Monday and will spend a week at the company's Menlo Park headquarters, before moving to California permanently in the new year.
The British firm, which worked on US President Donald Trump's 2016 election campaign, was found to have harvested the data of 87 million Facebook users.
Facebook is also facing the threat of increased government regulation - including from Europe, where Mr Clegg served as a commissioner - and in recent months, several executives have left the company.
Mr Schrage will stay as an adviser, Facebook said.