Police and soldiers maintained a low profile as the "Shutdown Bangkok" drive got under way in the city of about 12 million people. The mood was festive, with many protesters singing and dancing in the streets.
Major intersections that normally teem with cars and trucks were blockaded, but trains and river ferries were operating, most shops were open and motorbikes plied the roads freely.
Protest leader Suthep Thaugsuban said: "Don't ask me how long this occupation will last. We will not stop until we win."
As the blockade began to bite, Ms Yingluck invited the protest leaders and political parties to a meeting tomorrow to discuss an Election Commision proposal to postpone the vote.
But the protesters have rejected any election and want to install an appointed "people's council" to change the electoral system and bring in reforms to weaken the influence of her brother Thaksin Shinawatra's sway.
Political analyst Sukum Nuansakul said: "This won't end easily and the turnout today is impressive, so it seems this deadlock looks set to continue."