Ten of Paris's 16 lines were shut and service on the others was disrupted.
Many workers cycled, walked or stayed at home, while free rides were on offer on transport operator RATP's e-moped and Uber's e-bike and scooter networks.
The strike, the biggest since 2007, is the first big act against President Macron's plan for a universal pension.
It would replace dozens of different pension schemes for different professions.
Members of other professions including lawyers, airline staff and medical workers have called for more strikes starting on Monday.
There were 235km (145 miles) of traffic jams in the Paris region, officials said, more than double normal levels.
Local media showed photos of crammed platforms on four metro lines, where some trains were running.
Le Parisien newspaper said a legal requirement to maintain a minimum level of service - in place following a big strike in 2007, which was also against a pension overhaul - was not being fulfilled.
Three of the city's five regional rail lines, run by national rail operator SNCF, were running as normal but the two other lines were offering a reduced rush hour service and no trains at all during the rest of the day.
Travellers reported a surge in prices on ride-hailing services, with one journalist posting a screenshot showing a ride across the city costing €100 (£90), about three times the usual fare.
However Uber was also offering two free 15-minute rides on its Jump electric bikes and scooters in the city. RATP meanwhile was offering free 30-minute rides on the Cityscoot network of electric mopeds.
Paris has about 20,000 electric scooters available for hire.