The official language of South Sudan is English. Colloquial Arabic is spoken widely, and Juba Arabic, a pidgin, is spoken around the capital.

The population of South Sudan is composed of more than 200 ethnic groups and is, along with the adjacent Nuba Hills, one of the most linguistically diverse regions of Africa. However, many of the languages have only a few thousand speakers.

The most populous language by native speakers is Dinka, a dialect continuum spoken by 2–3 million people. Dinka is a Western Nilotic language; closely related to it is South Sudan's second most populous language, Nuer, and a bit more distant is Shilluk. Major Eastern Nilotic languages are Bari and Otuho. Besides the Nilotic family, Zande, South Sudan's third most populous language, is Ubangian. Jur Modo is of the Bongo-Bagirmi family.

A group of South Sudanese refugees who were raised in Cuba during the Sudanese wars, numbering about 600, also speak fluent Spanish. They have been named the Cubanos, and most had settled in Juba by the time of the country's independence.