The first phase of the campaign will begin in Kabul on June 24, targeting 850,000 people, before moving to Jalalabad, Mazar and Ghazni in following weeks.
Each phase lasts 20 days, and will involve hundreds of community health workers, teachers and religious leaders taking key health and hygiene messages directly to households.
About 50,000 children under the age of five die every year in Afghanistan of diarrhoeal diseases.
'Too many children die every year from preventable diarrhoeal disease,' UNICEF officer responsible for hygiene promotion, Zahida Stanekzai said.
"While the risks from diarrhoeal disease are high at this time of year, its prevention is relatively simple," Stanekzai said.