"The numbers we have experienced in the past two days are markedly down over what they were prior to the end of Title 42," Mayorkas said on CNN's "State of the Union" program.
He said there were 6,300 border encounters on Friday and 4,200 on Saturday, but cautioned it was still early in the new regime.
Mayorkas credited the criminal penalties for migrants who illegally enter the country, which resumed under existing law after Title 42's expiration, for the decrease in crossings.
Officials from communities along the border agreed they had not seen the large numbers of migrants that many had feared would further strain U.S. border facilities and towns.
Just before Title 42 expired on Thursday, House Republicans approved legislation that would require asylum seekers to apply for U.S. protection outside the country, resume construction of a border wall and expand federal law enforcement efforts.