The sudden change of policy came after days of economic crisis in the South American state, the BBC reported.
In a national broadcast, Maduro claimed his country was victim of international sabotage, which prevented new 500-bolivar currency notes arriving in time.
Many Venezuelans spent several days in long queues trying to hand in or swap the old notes.
Thousands of shops were closed because of the cash crunch, and the public were forced to rely on credit cards or bank transfers. Many were left without food.
Anger spilled over on to the streets and skirmishes were reported in six cities. Many were taken into custody.
In Caracas, people waved their 100-bolivar bills in the air and chanted “they’re useless!” – then turned and ran as police in riot gear fired tear gas.
The government said the scrapping of the 100-bolivar note was necessary to prevent smuggling.
The president said the aim was to tackle gangs which hoard Venezuelan currency abroad, a move he previously described as part of the “economic war” being waged against his government.