Microsoft has announced it is buying the professional networking website Linkedin for 26.2 billion US dollars (£18.5 billion).
The technology giant said the boards of both companies have unanimously approved the deal, which is expected to be complete at the end of the year subject to approval from regulators and Linkedin shareholders.
It said the deal will see it snapping up the social media company for 196 US dollars per share (£138) in an all-cash transaction.
The move will see current Linkedin chief executive Jeff Weiner holding on to his post and reporting to Microsoft CEO Satya Nadella.
Mr Nadella said the deal would "accelerate the growth of LinkedIn, as well as Microsoft Office 365 and Dynamics as we seek to empower every person and organisation on the planet".
Linkedin has seen its global membership grow by just under a fifth year-on-year to 433 million, while the number of active job listings on the site has climbed 101% year-on-year to more than seven million.
The social media firm - which has launched a new version of its smartphone app in the past year - now sees 60% of its users coming through mobile.
Mr Weiner said: "Just as we have changed the way the world connects to opportunity, this relationship with Microsoft, and the combination of their cloud and LinkedIn's network, now gives us a chance to also change the way the world works.
"For the last 13 years, we've been uniquely positioned to connect professionals to make them more productive and successful, and I'm looking forward to leading our team through the next chapter of our story."
The takeover will become one of the biggest deals in Microsoft's history, overshadowing its swoop for internet phone service Skype for 8.5 billion US dollars (£6 billion) in 2011 and its 7.2 billion US dollar (£5.1 billion) deal for Nokia's devices business in 2014.
Shares in Linkedin soared 47% on the New York Stock Exchange. Microsoft shares were down 3% following the announcement.
The tie-up comes after the social media firm saw close to 11 billion US dollars (£7.8 billion) wiped off its market value in February when shares plunged more than 43% after its revenue forecasts came in below analyst expectations.
Investors on Wall Street took flight after it forecast full-year revenues to hit between 3.6 and 3.65 billion US dollars (£2.5 billion and £2.6 billion), falling short of analyst predictions of around 3.91 billion US dollars (£2.8 billion).
Linkedin, which is based is based in Mountain View, California, floated on then stock market in May 2011.