Since launching in October 2018, TBM Nancy has tunnelled 6.8 kilometres via the new metro stations at Waterloo, Central and Pitt Street.
TBM Nancy will spend a few weeks under maintenance before being re-launched to complete the last 1.3-kilometre section between Martin Place and Barangaroo.
Caverns for the new Martin Place Station took 21 months to build with 198,000 tonnes of rock removed, enough to almost fill 30 Olympic swimming pools.
Premier Gladys Berejiklian said this historic milestone means 22 kilometres of the Sydney Metro tunnels have been completed in just 11 months.
“While people are getting on with life in the city above, deep underneath the CBD giant machines like TBM Nancy are getting on with the job, building tunnels for our future metro rail," Ms Berejiklian said.
Minister for Transport Andrew Constance said the tunnelling is pivotal to a well-connected public transport system in Martin Place.
“Customers will be able to transfer between the new metro and the Eastern Suburbs and Illawarra line,” Mr Constance said.