The world's largest refugee camp will close in November, Kenya's Interior Minister Joseph Nkaisserry has announced.
The Dadaab camp in Kenya is home to more than 300,000 Somalis.
Mr Nkaisserry said Kenya would work closely with the UN and the Somali government to repatriate the refugees.
Dadaab was set up in 1991 to house families fleeing conflict in Somalia, and some people have been living there for more than 20 years.
Kenya says it wants to close the camp over security concerns, saying attacks on its soil have been planned there.
Mr Nkaisserry said the decision was final.
Kenya did not follow through on a previous threat to close down the camp, made last April following the deadly attack by Somali militant group al-Shabab on a university 100km (62 miles) away.
The al-Qaeda linked group has staged several attacks on Kenya in recent years.
Kenya has set aside $10m (£6.8m) for repatriation, which Mr Nkaisserry insisted would carried out in a humane manner.