The extension to Sydney's light rail network will be operating by the end of next week.

The existing service from Central Railway Station to the inner-west suburb of Lilyfield will extend to Dulwich Hill from Thursday.

The opening will add nine stations to the line that first opened in 1997.

The new section of the line has undergone about 250 hours of testing over the past month.

Commuters will be able to catch a service every 10 minutes during the morning and evening peaks - between 7:00am to 10:00am then 3:00pm to 6:00pm.

Services run every 15 minutes at other times during the networks operating hours from 6:00am to 11:00pm.

Transport Minister Gladys Berejiklian says the ride from Dulwich Hill to Central will take about 40 minutes and the fare will be good value.

"Ticket prices will be exactly the same as what they are now, which is great news," she said.

"If you are currently paying a fare to get from Central to Lilyfield you won't pay anymore to go all the way to Dulwich Hill, so we've made sure this new extension is affordable."

Ms Berejiklian says the $176 million project will be completed on time and on budget.

A new-look light rail fleet will also be unveiled at the extension's opening, with new trains coming on line in the coming months.