Bollywood director Farah Khan, cricketer Yuvraj Singh and 'Hari Puttar' film famed child actor Zain Khan, were among others to pledge their allegiance to the cause.
"I wash my hands because so much of dirt is accumulated on my hands. UNICEF and Lifebuoy have given me a great opportunity to be part of this event. I am still beaten by my mother if I don't wash my hands," said Yuvraj Singh.
Globally, South Asia has the worst sanitation indicators and six of the eight countries in the region are not on target to meet the Millennium Development Goal.
The region has the highest rate in the world of people using no toilet at all - 48 percent of the population - with some 778 million people still relying on open defecation, the riskiest sanitation practice of all.
Of the approximately 120 million children born in the developing world each year, half do not have access to improved sanitation, jeopardising their survival and development, according to a WHO document.
Poor hygiene and lack of access to sanitation together contribute to about 88 percent of deaths from diarrhoeal diseases - 1.5 million diarrhoea-related under-five deaths each year - the document states.
Making hand washing with soap a habit could save more lives than any single vaccine or medical intervention, cutting deaths from diarrhoea by almost half and deaths from acute respiratory infections by a quarter, states the document.