Schiff, a Democratic lawmaker from California, would be the House "lead manager" at Trump's Senate trial expected to begin on Tuesday, Pelosi said.
Schiff led the House investigation that resulted in Trump's December 18 impeachment for abuse of power and obstruction of Congress.
Six other House lawmakers were named as managers: Jerry Nadler of New York, Zoe Lofgren of California, Hakeem Jeffries of New York, Jason Crow of Colorado, Val Demings of Florida and Sylvia Garcia of Texas.
Pelosi said a resolution would be voted on later Wednesday in the House formally naming the managers and transmitting the articles of impeachment to the Senate.
"The president of the United States is not above the law," Pelosi said. "He will be held accountable."
Meanwhile, President Donald Trump derided his impeachment as a "con" as Democratic leaders announced the team that will lead the trial in the Senate.
Here we go again, another Con Job by the Do Nothing Democrats. All of this work was supposed to be done by the House, not the Senate!