"Hello, Twitter! It's Barack. Really! Six years in, they're finally giving me my own account," Obama tweeted from his verified @POTUS account.
A Twitter spokesman could not immediately confirm whether Obama had set a record. According to Guinness World Records, the fastest pace to a million followers was set by actor Robert Downey Jr. in 23 hours and 22 minutes in April 2014.
Obama and his advisers pioneered the use of social media like Twitter and Facebook in the 2008 presidential campaign and have embraced their use in the White House as well.
As media attention has increasing shifted towards the 2016 presidential campaign, the White House has boosted its use of social media to break and shape news.
On Monday, the White House tweeted a short video of Obama sending his tweet from the Oval Office, perched on the edge of the historic Resolute presidential desk.
He used a White House iPhone to send the tweet, not his own high-security custom Blackberry. "I can't use phones with recorders in them," he explained on "Jimmy Kimmel Live" earlier this year.
It's not the first time Obama has tweeted. He has occasionally signed tweets from the @WhiteHouse account (6.2 million followers) with his initials, "-bo" and also has used @BarackObama (59 million followers), an account run by Organizing for Action, Obama's former campaign team.
But the @POTUS account will be "a new way for President Obama to engage directly with the American people, with tweets coming exclusively from him," said Alex Wall, a social media strategist with the White House, in a blog post.
His Twitter page featured an image of Obama in Selma, Alabama, on the 50th anniversary of the Bloody Sunday march earlier this year.
Obama followed a carefully curated list of his alma maters, his beloved Chicago sports teams, cabinet members, government departments, and White House staffers.
Of course, he followed @FLOTUS, the account used by first lady Michelle Obama.
Obama also followed former presidents George H. W. Bush and Bill Clinton, but is so far not following @HillaryClinton, his former Secretary of State who is considered the front runner for the Democratic presidential race for 2016.
Bill Clinton (3.4 million followers) tweeted to welcome Obama. "One question: Does that username stay with the office? #askingforafriend"
Obama replied: "The handle comes with the house. Know anyone interested in @FLOTUS?"
© Thomson Reuters 2015