The DWP estimates that around £400m ($576.6m, €506m) of unclaimed pension savings are waiting to be claimed.
The website can be accessed here.
Users will need the name of an employer or provider to access the service, which will then search a database of 320,000 pension scheme administrators and come up with contact details for people to use.
The department believes that recent reforms in the UK, allowing people unrestricted to access to their pension savings, will drive demand for the pension tracing service.
Pensions minister Ros Altmann said: “People have had on average 11 jobs during their working life which can mean they have as many workplace pensions to keep track of.
“The new DWP online service helps reunite people with their lost pensions, giving details of providers to help people track them down.”
Case study
Using the new website, London-based Yvonne Mavin discovered she had a £10,000 pension pot with Aviva.
She said: “There was one employer who I worked for about 30 years ago and I knew I had a pension with them of some sort. But as it was so long ago, I had just lost track of it.
I used the pension tracing service in early 2016 and within two weeks I managed to trace a £10,000 pension with Aviva.
“I had actually put off trying to trace my pensions because I thought I would need lots of details. But when I got round to doing it I was shocked how easy it was.”
Hargreaves Lansdown
Tom McPhail, head of retirement policy at Hargreaves Lansdown, said: “The pension tracing service will help people track down lost pension pots and can dovetail with the forthcoming development of the expanding Pension Wise service.
He called on the government to go further and alter the terms of auto-enrolment so that employees can select a product into which their employer pays their pension contributions.
McPhail revealed that the government and pensions industry in the UK is also working on a pension dashboard which would help investors view all their pension pots in one place
