Mayorkas, who served as deputy secretary at the Department of Homeland Security (DHS) under president Barack Obama, was sworn after the deadly January 6 riot at the US Capitol by supporters of outgoing Republican president Donald Trump.
"To see the insurrection, to see the horrific acts of January 6 were not only personally devastating, but... that created in me a commitment to redouble our efforts to fight hate and to fight one of the greatest threats that we face currently on our homeland, which is the threat of domestic terrorism," Mayorkas told CNN in an interview that aired Saturday evening.
Mayorkas also said the Biden administration was working with "due urgency" on efforts to end a Trump-era policy known as the Migrant Protection Protocols (MPP), which forced more than 65,000 asylum seekers back to Mexico to wait for US immigration court hearings.
"We are looking at that as recently as earlier today," he said. "The urgency of that also cannot be overstated."
When asked about recent hacks by Chinese and Russian groups of US government computer systems, Majorkas said the administration was working with Congress to see what additional funding could be provided to enhance the security of federal infrastructure and information systems, as well as through public-private partnerships.