US authorities have arrested almost 1,200 people in what they say is the largest raid of its kind on migrants working illegally in the country.
Mr Chertoff said he is getting tough on illegal migrant workers
The alleged illegal immigrants worked for the same crate company and were held in nine different states.
Homeland Security Secretary Michael Chertoff said the raid was a warning to workers and employers "who tolerate or perpetuate a shadow economy".
The US Senate has been deadlocked over plans to reform immigration rules.
The Senate is due to resume its debate in a few days.
President George W Bush has proposed the introduction of a "guest-worker" scheme - but this faces stiff opposition from some in his own Republican party who see it as being too soft on lawbreakers.
According to the BBC's Washington correspondent, James Coomarasamy, the latest raid is clearly designed to counter that impression.
The target of the raid was Ifco - a German-based company that specialises in the manufacture of crates.
Plans to criminalise illegal migrants have sparked huge protests
Seven officials from the company were among those arrested.
"Employers and workers alike should be on notice that the status quo has changed," Mr Chertoff said.
He said his department would use every authority within its power "to shut down businesses that exploit an illegal workforce to turn a profit".
He added that those who entered the US illegally could not be allowed to think they were safe once they were inside the country.
Mr Chertoff said his department planned to increase the number of illegal immigrants deported from the US and prosecute more US firms that employed them.
An estimated 11.5 million illegal immigrants are believed to be living in the US.
Recent efforts to criminalise their status have triggered nationwide protests from pro-immigrant and Hispanic groups.