Most of Sierra Leone's population of six million were confined to their homes from midnight, with only essential workers such as health professionals and security forces exempt from the lock down.
Almost 30,000 volunteers will go door-to-door to educate locals and hand out soap, in an exercise that could lead to scores more patients and bodies being discovered in people's homes.
Health experts have criticised the shutdown, arguing that coercive measures to stem the epidemic could backfire and would be extremely hard to implement.
But Sierra Leone President Ernest Koroma said that if the population were to heed the volunteers' advice, "the campaign will greatly help to reverse the increasing trend of the disease transmission and become a very big boost to our collective effort to stop the outbreak."
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"These are extraordinary times and extraordinary times require extraordinary measures," added Koroma in a message broadcast on television and radio.
The extreme move comes amid mounting global concern over the Ebola epidemic, which has so far killed more than 2,600 people in west Africa.
In New York, the 15-member United Nations Security Council unanimously adopted a resolution declaring that the "unprecedented extent of the Ebola outbreak in Africa constitutes a threat to international peace and security".
It called for immediate aid and urged nations to lift travel and border restrictions, and asked airlines and shipping companies to maintain their links with affected countries.