Manhattan echoed to the sound of chants, horns and drums as the colourful protest progressed through the streets.
Organisers of the Manhattan event said it surpassed the largest previous protest on climate change.
They said the massive mobilisation was aimed at transforming climate change "from an environmental concern to an everybody issue".
Business leaders, environmentalists and celebrities joined the demonstration.
Hollywood actor Leonardo DiCaprio also took part, having been appointed as a UN representative on climate change last week.