The leading Democrat in the U.S. Senate promised Friday to vigorously oppose this nomination.
Miller played a decisive role in carrying out the mass deportation program during Donald Trump's second term, often characterized by violent raids conducted by masked agents.
He drew particular criticism after the fatal shootings of two protesters by immigration agents in Minneapolis in January, incidents that triggered mass demonstrations.
U.S. President Donald Trump announced Friday that his adviser Stephen Miller would become his new chief of staff.
Miller embodies, within the presidential inner circle, the identitarian and restrictive line on immigration.
This nomination further tightens the inner circle around the president.
He also holds the title of homeland security adviser.
Miller, 41, a hyperloyalist, has been one of Mr. Trump's closest aides for more than a decade. He is described as the president's most powerful and uncompromising voice on immigration.