The former Liberal Democrat leader party, who served as David Cameron's right-hand man between 2010 and 2015, will succeed Elliot Schrage as the company's head of global affairs and communications.
Sir Nick was took the role after "months of wooing" by Facebook CEO Mark Zuckerberg, according to the Financial Times which broke the story.
But Sir Nick appeared to pitch for the post over a year ago in a fawning column that denounced media criticism of the social media giant.
Defending Facebook in a September 2017 column for the i newspaper, he wrote: "It's time we pause for breath before everyone charges off in a stampede of condemnation of tax-dodging-fake-news-extremism-promoting-data-controlling tech firms. The unthinking mood of hostility could soon topple into outright Luddism against new forms of technology."
At the time the company was facing criticism for their role in spreading political misinformation and extremist content.
Sir Nick's role will now be to try and alter that narrative.
What will he do?
In his new role, Sir Nick will be tasked with fighting many of the issues he laid out in his 2017 column.
"We need a new deal between the tech world and politics: tech companies need to embrace, not shun, new ways for people to control their personal data, new ways to challenge fake news, and to accept greater scrutiny of the immense power they wield over over markets, and of the taxes they pay," he wrote.
"Governments, old fashioned media, and the public at large need to avoid a knee-jerk condemnation of the disruption and potency of new technologies, and embrace the idea that technology can improve our lives."
In order to do this, he will be able to draw on his extensive experience as a former European Commission trade negotiator and member of the European Parliament, which will serve him well in any future dealings with Brussels.
Why does Facebook need him?
Mr Clegg's appointment follows a series of high-profile scandals at the social network, most recently a massive data breach that compromised the personal information of 30 million Facebook users.
Part of his new role will be dealing with the political and societal implications of such controversies, attempting to shape political regulation that will inevitably result from investigations into the data breaches and other incidents.
"Facebook, WhatsApp, Mesenger, Oculus and Instagram are... at the heart of some of the most complex and difficult questions we face as a society: the privacy of the individual; the integrity of our democratic process; the tensions between local cultures and the global internet; the balance between free speech and prohibited content; the power and concerns around artificial intelligence; and the wellbeing of our children," Sir Nick wrote in a Facebook post announcing his appointment.
"I believe that Facebook must continue to play a role in finding answers to those questions – not by acting alone in Silicon Valley, but by working with people, organisations, governments and regulators around the world to ensure that technology is a force for good."
Where Sir Nick is less experienced is in US politics, although his appointment will be seen by some as a positive move on the part of Zuckerberg, as it shows he is willing to open up his inner circle in order to address the crises affecting his company.
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