In a memo that describes an "urgent humanitarian situation," Obama has put the Federal Emergency Management Agency in charge of coordinating humanitarian relief to the children, including housing, care, medical treatment and transportation.
The Obama administration estimates that about 60,000 "unaccompanied minors" - children under 18 - will enter the United States illegally this year. It projects that number to grow to nearly 130,000 next year.
As recently as 2011, the number was only some 6,000.
Many of the children are from Honduras, El Salvador and Guatemala, as well as Mexico, and are fleeing either domestic abuse or violent gangs that increasingly prey on children as young as 12, White House officials said.
Poverty also contributes to decisions to leave their home countries, according to immigration advocacy groups.
In making the journey to the United States, they often are trying to reunite with a parent or other relative.
Last month, the administration announced it had opened a temporary shelter for some of the children at Lackland Air Force Base in San Antonio. It is nearly at its capacity of housing 1,200 children, officials said.
Reflecting the urgency of the situation, another such facility will open at Naval Base Ventura County in Southern California, Mark Greenberg, assistant secretary at the U.S. Department of Health and Human Services, said on Monday.
The California facility will hold a maximum of 600 children, officials said.
White House Director of Domestic Policy Cecilia Munoz said the action being announced on Monday was prompted not only by the rapid increase in the number of unaccompanied children, but because there were more girls than before and more children under the age of 13 than in past years.
The growing numbers of unaccompanied minors are placing budgetary pressures on Congress and the Obama administration as they prepare spending bills for next year, Reuters reported last week.
The officials did not provide an estimate of how many new shelters would have to be provided or the overall numbers of children that will have to be housed.
Homeland Security Deputy Secretary Alejandro Mayorkas said federal officials would focus resources on combating smuggling networks that bring the children into the United States and would work with Central American governments to spread the word that the journey from their home countries is "perilous."
Many children do not realize the dangers they can encounter in leaving their home countries, including sexual assaults, starvation, forced labor and injuries from falling from freight trains that they jump on in Mexico.