STORY: Garland's announcement came three days after Trump, a Republican, announced he would run for president again in 2024.
Trump told a crowd of supporters at a black tie event at his Mar-a-Lago estate in Florida that this was a "horrendous abuse of power".
He called the developments the "latest in a long series of witch hunts that started a long time ago" as he brought up other investigations into his conduct in office.
Biden did not respond to shouted questions from reporters about the special counsel during his only public appearance of the day. The White House was not involved in the decision to appoint Smith, an official said, speaking on condition of anonymity.
Smith, a political independent, until recently served as the chief prosecutor for the special court in The Hague, tasked with prosecuting war crimes in Kosovo. He previously oversaw the Justice Department's public integrity section and worked as a federal and state prosecutor in New York.