The office says it will also include rough sleepers
The Central Statistics Office (CSO) say homeless people will be included on the 2016 Census on April 24th.
The CSO says its clarification follows recent comments "suggesting that homeless people will not be enumerated in Census 2016".
"Every person in Ireland must be included on a census form on Sunday, 24 April. This includes homeless people", it says.
The census provides information on a wide range of topics and issues, and is used in the development of policy by every government department and local authority in the country.
"The formulation of policy on addressing the country's homeless problem requires accurate information on the number of homeless people and their location. The census is the appropriate way of gathering that information", it says.
The CSO says it is aware of the "increased complexity" of the homeless situation in Ireland.
It adds that it has been working for the past 18 months on the most appropriate methodology for enumerating homeless people in a variety of settings - including rough sleepers.