A month after launching the under-city driverless trains, Transport Minister Jo Haylen says services will run every five minutes instead of seven, between 10am and 3pm.
Trains will also run past midnight every night except Sunday, under the changes, starting on Monday.
The government says the boost in the service is in response to around five million passenger journeys being made on the $21 bilion line since it opened on August 16.
"A train every five minutes during the day and services running until after midnight almost every night means more people can jump on the metro to enjoy everything Sydney has to offer, from the north to the inner west," Ms Haylen said in a statement.
Jo Haylen says commuters can now expect a train every five minutes during the day. (Jeremy Piper/AAP PHOTOS)
"We expect this boost in services will see even more people using the metro to commute, explore and keep our great city thriving well after the sun goes down."
Commuters have taken around 200,000 trips each day on the metro since it opened.
The cross-city extension, which runs from Chatswood in Sydney's north to Sydenham in the inner west via tunnels under Sydney Harbour, forms part of a metro network that is the largest public transport project in Australia.
The project faces upcoming disruption from the NSW Rail, Tram and Bus Union which has threatened to suspend work on the T3 Bankstown Line from September 18 if the state government does not negotiate on work to convert the heavy rail line to a metro.