More than 20 illegal immigrants will be sent back to India and their employer faces a massive fine following a raid in Southall.
The UK Border Agency carried out the operation, targeting G&B Windows in Johnson Street, on Thursday.
Twenty-two Indian men, aged between 21 and 47, were found to be working illegally and were arrested.
One man has been charged with offences under the Identity Cards Act after he was found to be in possession of a forged document. Steps are now being taken to return all 22 employees to India.
The employer now faces a fine of up to £190,000. Three other individuals, who claimed to be self-employed, might each have to pay £10,000 fines
Acting on intelligence received about possible illegal working at the business, around fifteen immigration officers obtained a warrant to question staff and managers on site.
Alex Legg, chief immigration officer, said: "As long as there are illegal jobs, the UK will be an attractive place for illegal immigrants. That's why we have to put a stop to employers who don't play by the rules."
Changes were introduced in February this year which mean employers can face fines of up to £10,000 per illegal worker if pre-employment checks are not carried out correctly.
The UKBA is also introducing ID cards for foreign nationals before the end of the year. ID cards will help employers and public authorities identify who has permission to work.