It is the largest city in Indian River County and the biggest population center between Palm Bay and Fort Pierce.

[11] Sebastian is a principal city of the Sebastian−Vero Beach Metropolitan Statistical Area, which includes all of Indian River County.

Nearby Pelican Island was declared the first National Wildlife Refuge in the United States in 1903.

[14] According to the United States Census Bureau, the city has a total land area of 13.66 square miles (35.4 km2).

Members of the city council serve two-year terms with staggered elections.

Indian River County Fire-Rescue provides fire protection and emergency medical services to the citizens of Sebastian.

It operates from the municipal complex, and has an authorized strength of approximately 48 sworn officers.