Road safety group Brake developed the pledge, which breaks the key elements of road safety into 12 'commandments' in an attempt to cut fleet-related road accidents.
So far, 28 companies have joined the scheme, securing almost 14,000 driver pledges, although Brake has approached 'a few hundred' companies about participating.
Mary Williams, Brake chief executive, said: 'It is encouraging that these major companies are asking their drivers to sign the pledge. One in three deaths on the road involve a vehicle being driven for work. If all company drivers signed the pledge, and stuck to it, many deaths would be prevented.
The pledge is backed up by posters, window stickers, badges, a risk management guide and Powerpoint presentation for fleet managers to show drivers.
Each month, Brake will send out a leaflet highlighting a danger that drivers could face. The pack costs 30 pence per driver.
Steve Gay, head of health, safety and environment for Transco, which has 500 drivers, said: 'Road safety is extremely important to us, which is why we support the Brake initiative and why we will continue to look for ways of encouraging all our staff to think safety when they are on the road.'
John Roberts, chief executive of water company United Utilities, said: 'Our employees drive millions of miles in the course of their work. By asking them to sign up to the pledge, we are encouraging them to all do their bit by driving safely at all times.'
For further details, check out www.brake.org.uk