The ceremony to open the 39-kilometre Mitcham-to-Frankston tollway was held on Saturday, but the first cars did not get on the road until yesterday.

The tollway, which features 17 interchanges, 88 bridges, a 35-kilometre shared-use path and twin 1.6-kilometre three-lane tunnels, was opened five months ahead of schedule.

Premier John Brumby said the roadway would transform travel around Melbourne, delivering massive economic and social benefits for Victoria.

"EastLink is the largest ever single addition to the Melbourne transport network and its early opening will provide time, fuel and vehicle efficiency savings for Victorians.''

Mr Brumby said EastLink was the biggest road project in Australia during its construction and its completion in just 39 months made it the most successful ever delivered in the state.

He said people in Melbourne's outer east and south-east had waited almost 40 years for EastLink to become a reality.