A government campaign will warn bosses that they face large fines and prison sentences if they are caught employing illegal migrant workers.
The government has issued a code of practice for businesses
The Home Office will run radio and print adverts ahead of a tightening of the law on illegal labour in February.
Employers could be fined up to £10,000 for every illegal worker they negligently hire, or could face up to two years in prison.
The immigration minister said firms would have no excuse to break the law.
Liam Byrne said: "Illegal working attracts illegal migrants and undercuts British wages. That's why we're determined to shut it down.
"The message is clear for employers - we will not tolerate illegal working."
In 2006, the Border and Immigration Agency (BIA) said it carried out more than 5,200 operations targeting illegal working and removed more than 22,000 people from the UK.
The campaign posters focus on the catering and road haulage industries, with the message: "If you hire illegal migrant workers you're as illegal as they are."
The catering industry is one of those targeted by the campaign
One shows a lorry with the words "U R Nicked" on the side and the other a cafe called "Arrestaurante".
Radio adverts feature a restaurant owner agreeing to pay an illegal worker cash-in-hand to wash dishes.
From February, employers found to be breaking the law could lose the right to recruit from outside the European Union.
The BIA has issued a code of practice for employers on how to identify an illegal migrant worker without infringing race discrimination laws.
And it warned businesses that this code of practice could be used against them in court if they are accused of carrying out checks on workers purely on the basis of race or ethnicity.
The three-week advertising campaign will begin on 14 January.
The government crackdown is part of a range of measures being introduced this year including an Australian-style points system for managing immigration and biometric identity cards for any foreign national in the country for more than three months.
Earlier this month, the Home Secretary Jacqui Smith admitted that as many as 11,000 illegal immigrants may have been cleared to work as security staff.
That was an increase on the figure of 5,000 disclosed in November.