Juba's application presented to Arab League foreign ministers in Cairo.
South Sudan has applied to join the Arab League, the Sudan Tribune has reported.
Juba's formal application was presented to the League's foreign ministers in the Egyptian capital, Cairo on Wednesday.
The bloc's member states include countries in North Africa, the Horn of Africa and Arabia.
If successful, South Sudan will join Algeria, Comoros, Djibouti, Egypt, Mauritania, Somalia, Sudan and Tunisia as the League's ninth African state and 23rd member.
South Sudan has long wanted to join the group, which requires member states to use Arabic as an official language.
The country seceded from Sudan in 2011.
Arab League was founded in 1945 and is headquartered in Cairo.
South Sudan is also a member of the East African Community alongside Kenya, Uganda, Rwanda, Burundi and Tanzania.
The bloc's official language is English while Kiswahili is the lingua franca.
-Additional reporting by BBC.