"Over the past two days, the US border patrollers experienced a 50% drop in the number of encounters versus what we were experiencing earlier in the week before Title 42 ended at midnight on Thursday," he told American TV channel.
"It is still early. We are in day three. But, you know, we have been planning for this transition for months and months," he said, adding it was too early to say whether the surge had peaked.
Title 42 restrictions were implemented under President Donald Trump in response to the COVID-19 pandemic to allow for prompt deportations of illegal migrants to Mexico or their origin countries.
Mayorkas said that US border patrol agents stopped 6,300 people from crossing illegally into the United States on Friday and 4,200 on Saturday. Over 10,000 attempted to cross earlier last week, before Title 42 expired.
He put the surprise decrease in illegal entries down to stricter punishments, including deportations and a five-year ban on entry, for illegal immigrants coupled with more lawful and safe ways for legal immigration.