Early reports said buses and taxis were off the roads, and shops and restaurants remained closed. Train services were not affected.
The Congress-led UDF government has declared 'dies non' (no work, no pay) as pro-Left service and teachers unions are also striking work.
Security has been tightened and no violence has been reported from anywhere. Police have offered protection to those willing to work and public conveyances ready to ply, police sources said.
Emergency services like health care, milk supply and media have been exempted from the strike, AITUC leader Kanam Rajendran said.
The unions have put forward a charter of 10 demands such as urgent steps to control price rise, strict enforcement of labour laws in all places of work, social security net for workers in the unorganised sector, end to disinvestment in PSUs and raising minimum wage to Rs 10,000 a month.
Apart from unions owing allegiance to the Left, the pro-Congress INTUC and pro-BJP BMS are also participating in the strike.
However, pro-UDF government service and teachers unions have not joined the strike.