It took 6 years to fire off his first tweet.
The Goldman Sachs CEO, who has been a member of Twitter since June 2011, fired off his first tweet Thursday in response to Trump's decision.
@lloydblankfein Today's decision is a setback for the environment and for the U.S.'s leadership position in the world. #ParisAgreement
At first, it wasn't clear whether it was the real Blankfein tweeting since his account lacked a blue checkmark that signifies verified accounts. Yet, Goldman Sachs public relations quickly confirmed that it was Blankfein's account that it was indeed his first tweet. The blue checkmark quickly appeared on his Twitter page, and he gained hundreds of followers within an hour after his tweet.
This isn't the first time Blankfein has expressed criticism of Trump policies. In January, the CEO told employees at Goldman Sachs that the Wall Street heavyweight doesn't support Trump's ban on immigration from certain Muslim-majority countries.
Last month, Blankfein told CNBC that he was proud that Trump selected so many Goldman Sachs alums for his administration, but added that he was "a little apprehensive about it because for fear of how it might look."
Former Goldman president and operating chief Gary Cohn serves as Trump's main economic advisor, while former Goldman employee Steven Mnuchin is the secretary of the Treasury. Steve Bannon, another top Trump advisor, also worked at Goldman Sachs.
CNBC's Fred Imbert contributed to this report.