"Public safety is our number one priority," said Gov. Arnold Schwarzenegger.
Schwarzenegger joined local and state leaders along with law enforcement during Wednesday's ceremony.
The construction will be paid for with funding the governor approved in 2007 under the Public Safety and Offender Rehabilitation Services Act.
The detention center currently houses 700 inmates, but will expand to include an additional 1,300 beds.
"We are the first county in the state to be able to get the $100 million to expand this," said San Bernardino County Sheriff Rod Hoops. "The state has a severe overcrowding population. The Supreme Court's looking at releasing 40,000 inmates back into the communities. This will help a little bit with that."
The state is currently dealing with overcrowded and overburdened prisons.
The federal government has even stepped in and ordered the state to release prisoners, which doesn't sit well with law enforcement and the outgoing governor.
"I don't know why it is but some just feel like letting out inmates is the solution to that, of course which would be disastrous, because it would make our communities unsafe," said Schwarzenegger.
While the detention center in Adelanto is being built, the county must also build a second facility in Apple Valley, a 500-bed re-entry facility as part of the state funding agreement.
"It's a place where community volunteers, faith-based groups, licensed drug and alcohol counselors, job counselors come in, meet the inmates who are going to be returning to their homes in San Bernardino County," said Calif. Dept of Corrections and Rehabilitation Secretary Matthew Cate.
The construction project will help generate 500 jobs and another 200 permanent local jobs when completed in 2013.