Haulage firms have been made to pay £12.4m for illegally carrying migrants over the border, since the fines were introduced in 2008.
The latest Home Office figures have revealed £4.2 million of fines were collected in 2014.
This is an increase of more than four times over the year before, when just £1 million of fines were received.
The rules mean firms have to pay up to £2,000 for each stowaway found, regardless of whether the driver is aware of them.
It is expected that the number of fines will be higher still this year, due to record numbers of migrants congregating at key ports such as Calais.
Last week, following the strike of workers at Calais, 350 people were caught trying to board vehicles in just four hours.