The protestors have taken their lead from similar protests in other cities around the world including Madrid, Athens and New York.
La Défense, in the west of the capital, is home to some of France's biggest companies including the bank Société Générale, oil company Total and energy company EDF.
The area is known for its skyscrapers and the huge Grande Arche de la Défense which looks back towards Paris.
"There were 80 to 100 of us overnight and 100 of us today to discuss and sing," said one of the protestors, reported business daily Les Echos.
A number of groups, including Uncut France, Occupy Paris and the Indignés de la Bastille, have been involved in the protest. They claim the action is designed to "put an end to austerity, create a true democracy and build a new world."
French police appeared to be taking a harder line than forces in some other cities. One protestor claimed they had been forced to sleep "just in sleeping bags as the tents were confiscated by police."
Police claimed there were 40 protestors remaining on Monday morning.
For those planning on spending a fourth night outside, temperatures are expected to fall to 11 degrees Celsius (52 degrees fahrenheit).
View more photos from Occupy La Défense by Philippe Leroyer.