Eurotunnel is cutting prices to compete with high speed ferry operators.
Channel Tunnel operator Eurotunnel is currently battling huge debts
The Folkestone-based group is offering £100 return tickets for a car and passengers travelling to France until the end of the year.
The move comes just a month after SpeedFerries launched its cut price service, carrying cars from Dover to Boulogne from £50 return.
The Channel Tunnel operator, whose board was ousted by investors in April and then replaced, has debts of £6.4bn.
The lowest price being offered by Eurotunnel a few weeks ago was £173.
Passengers taking up the new deal will be required to travel to France after 1400 BST on the day of the outward journey and return before 1400 BST on any subsequent day.
They will have to book at least one day in advance.
Eurotunnel has denied that the offer is aimed at fighting off new rivals.
A spokesman said the initiative had been launched at the same time last year to attract late-booking summer holidaymakers.
"It is certainly not a response to SpeedFerries," he said.