In 2009, the company hit 50 million users and it has taken just over 18 months to get another 50 million.
The company says it now adds a new member every second.
As part of the milestone celebration, LinkedIn posted interesting figures about its membership base:
-56 percent of users are from outside the U.S. and growth remains stronger internationally than in the States.
-Brazil had the strongest growth, 428 percent year-over-year. Mexico, India and France followed.
-LinkedIn usage peaks at noon for desktop, 8pm for mobile devices.
-20 percent of users are in "service" sector, 9 percent are in finance and another 9 percent are in tech industry. There are also 1 million teachers.
When the company IPOs later this year, it is expected to fetch $3 billion.