Workers on the Paris metro and suburban rail networks are joining French national rail workers on strike, little more than a week before the Euro 2016 football championship is due to begin.
In addition, dock workers are expected to stop work and hold their own protest.
Trade unions are protesting against work time changes but the strike comes amid general labour unrest.
The wider protests are over a bill to shake up the labour market.
However, the disruption to public transport in Paris is expected to be limited.
On the national rail network, about 60% of high-speed trains and between a third and a half of other services were expected to be running, the state rail company the SNCF said.
The labour reform bill comes before the Senate this month, having passed through the lower house without a vote.
France's Socialist President, Francois Hollande, insists it will not be withdrawn despite months of unrest which erupted into street clashes between protesters and police at marches last Thursday.
However, leading conservative opposition politician Nicolas Sarkozy has accused him of getting "everything wrong from the start" in his handling of the crisis.
"Pushing [the bill] through by force cuts out debate," the former president told magazine Valeurs Actuelles. "If you don't accept the debate of ideas in parliament, then it moves to the streets."
The 35-hour week remains in place, but as an average. Firms can negotiate with local trade unions on more or fewer hours from week to week, up to a maximum of 46 hours.
Firms are given greater freedom to reduce pay.
The law eases conditions for laying off workers, which is strongly regulated in France. It is hoped companies will take on more people if they know they can shed jobs in case of a downturn.
Employers to get more leeway to negotiate holidays and special leave, such as maternity or for getting married. These are currently also heavily regulated.
Strike action led by the powerful CGT union began on Tuesday evening - the eighth railway strike in France in three months.
Commuters vented their anger with the SNCF on social media but a poll in the Journal du Dimanche newspaper suggested 46% of French people still support the unions' calls.
Air transport is also expected to be disrupted this month by industrial action not linked directly to the labour law reform.
The next national day of action by trade unionists is due on 14 June, when the labour reform goes to the Senate.
