The POTUS delivered his remarks after a raucous reception from the crowd in the Rose Garden at the White House. He preached a message of unity ... telling people to love the country even if their candidate didn't win, and love their neighbor even if they disagree on policy.

He also shot down any conspiracy theories regarding election fraud, and promised a peaceful transition of power in January.

Vice President Kamala Harris, the Democratic presidential candidate who lost the election this week, delivered her concession speech from Howard University in Washington, D.C. Wednesday.

Biden, who originally sought a second term before passing the torch to Harris in July, first responded to the election results Wednesday ... calling Trump to congratulate him, and praising Harris for running a campaign with "a strong moral compass and a clear vision for a nation."

He added ... "Her story represents the best of America’s story. And, as she made clear today, I have no doubt that she’ll continue writing that story."

Biden has made it clear he's determined to oversee the smooth transition of power for a new Trump administration ... following tradition by inviting the prez-elect to the White House during the call with 45 -- soon to be 47 -- something Trump himself notably did not do when he was president.