"It's been the honor of my life to serve you. You made me a better leader and a better man," he said.
His post-White House website, Obama.org, features a request form for scheduling events and a page for fundraising.
"As we look forward, I want our first steps to reflect what matters most to you. Share your thoughts with me at Obama.org," he tweeted.
"I won't stop; I'll be right there with you as a citizen, inspired by your voices of truth and justice, good humor, and love," Obama also tweeted.
The final tweet from the Obama administration's control of the account @WhiteHouse came shortly thereafter, and featured a photo of Obama hand-in-hand with Rep. John Lewis as well as other civil rights activists in Selma, Alabama, in 2015.
"Yes we can. Yes we did. Thank you for being a part of the past eight years," the account tweeted.
The tweets come as more than 50 Democratic lawmakers -- including Lewis -- are planning to boycott Donald Trump's inauguration out of concern for how he came to power following US intelligence pointing to Russia's involvement in meddling with the 2016 election. Trump tweeted after Lewis' announcement to boycott that the civil rights icon was "all talk."
And other lawmakers expressed concern about Trump's rhetoric and proposed policies towards women, immigrants, Latinos and other groups that overwhelmingly supported Hillary Clinton in the campaign.
"I'm still asking you to believe - not in my ability to bring about change, but in yours. I believe in change because I believe in you," Obama tweeted.
Obama wrote an emotional public letter, published Thursday, thanking Americans and encouraging them to participate into "daily acts of citizenship."
"Before I leave my note for our 45th president, I wanted to say one final thank you for the honor of serving as your 44th," he wrote. "Because all that I've learned in my time in office, I've learned from you. You made me a better president, and you made me a better man."