What county is Sebastian in — Sebastian, Florida

Sebastian, Florida is in Indian River County, where it is the largest city and sits at the county's northern edge along the Indian River Lagoon.

The U.S. Census Bureau 2020 Florida place codes file lists Sebastian city as an incorporated place in Indian River County, and the same file assigns the nearby census designated places of Roseland and Wabasso to Indian River County as well. There is no Sebastian County anywhere in Florida; the name belongs to the city, to the St. Sebastian River on its north edge, and to Sebastian Inlet on the barrier island to the east.

The confusion has a geographic cause. Sebastian sits at the very top of Indian River County, on the west shore of the Indian River Lagoon, and the Brevard County line runs along the river that forms the city's northern limit. Sebastian Daily pointed out in June 2018 that Barefoot Bay and a marina called Sebastian Inlet Marina are in Micco and Brevard County, not Indian River County, even though many people describe them as Sebastian. Inside the city, though, every lot from the Sebastian Highlands to the riverfront on Indian River Drive is in Indian River County, which collects the property taxes, runs the courts and keeps the official records that apply to Sebastian residents.

Sebastian is also the largest city in the county by population. The Census Bureau Vintage 2024 estimates put Sebastian at 27,087 residents in 2024, compared with 17,556 for Vero Beach, the county seat, and 172,139 for Indian River County as a whole.

The Brevard County line runs along the St. Sebastian River and the centerline of Sebastian Inlet, just north of the Sebastian city limits.

The line is written into state law. Section 7.31 of the Florida Statutes defines the north boundary of Indian River County by running east along a township line to the south fork of the St. Sebastian River, then down the thread of the St. Sebastian River to its confluence with the Indian River. From the river mouth the line crosses the lagoon to the approach channel of Sebastian Inlet and follows the centerline of the inlet out to the Atlantic.

That description explains the map. The city of Sebastian lies south of the St. Sebastian River, so it falls in Indian River County. Micco, directly across the river, is a census designated place in Brevard County according to the Census Bureau place codes file. On the barrier island, the inlet itself splits the two counties, so the beaches north of the inlet channel are in Brevard while the south jetty, Ambersand and the Wabasso Beach area are in Indian River County.

Several public bodies straddle the line because the water does. Sebastian Daily described Sebastian Inlet State Park in December 2023 as sitting at the border of Brevard and Indian River counties. The Sebastian Inlet District, the special district that maintains the inlet channel, is governed by a five-member commission with three Brevard County seats and two Indian River County seats, and property owners in both counties vote for those seats in November of even-numbered years.

Sebastian became part of Indian River County when the county was split from St. Lucie County in 1925, about six months after Sebastian incorporated.

Sebastian is older than its county. Sebastian Daily reports that the town was founded in 1882 under the name St. Sebastian, later dropped the St. from its name, and became an official municipality in December 1924. At that moment Sebastian was in St. Lucie County, because Indian River County did not yet exist.

The Indian River County centennial history explains that the land now in the county had earlier been part of St. Lucie, Brevard, St. Lucia and Mosquito counties. The residents of Vero opposed how St. Lucie County was spending its funding and objected to some of the blue laws enforced in Vero, so they went to Tallahassee to ask for a new county. The Florida Senate approved it in May 1925, the act took effect 30 days later, and Indian River County officially became a county on June 29, 1925. The new county even kept the elk seal it inherited from St. Lucie County, which the Indian River County Clerk of Court still uses.

Vero News summarized the result in 2009: Indian River County was created in 1925, it was named for the Indian River Lagoon that runs through its eastern portion, and its county seat is Vero Beach. Sebastian, a fishing and boat town on that same lagoon, came along with the new county from its first day.

Vero Beach is the Indian River County seat, and the clerk, the tax collector and the county library system all keep branch offices in Sebastian.

Vero Beach sits on the lagoon south of Sebastian. The Indian River County Clerk of the Circuit Court lists the Indian River County Courthouse at 2000 16th Avenue in Vero Beach, and the county commission lists county administration at 1801 27th Street in Vero Beach. Felony, civil and family cases and the recording of deeds for Sebastian properties run through the Vero Beach courthouse.

Several county constitutional officers keep branch counters in Sebastian so that north county residents do not have to drive south for routine business. The clerk lists a Sebastian Office at 1921 U.S. Highway 1, open Monday, Wednesday and Friday. The Indian River County Tax Collector lists its Sebastian Office in Sebastian Corners at 1921 U.S. Highway #1, where in-office services require an appointment.

The county library system also has a Sebastian branch. The Indian River County Library System lists the North Indian River County Library at 1001 Sebastian Boulevard, Sebastian, alongside the Main Library on 21st Street in Vero Beach and the Brackett Library. Because Sebastian is a city, its police, building permits, garbage contract and zoning come from the City of Sebastian rather than the county, while property appraisal, tax collection, elections, courts and libraries are county functions.

Sebastian is the most populous city in Indian River County, with an estimated 27,087 residents in 2024 on 17.4 square miles of land.

The Census Bureau Vintage 2024 subcounty estimates show Sebastian growing from an April 2020 estimates base of 25,034 to 27,087 in 2024. Over the same period Vero Beach went from 16,357 to 17,556, and Indian River County from 159,789 to 172,139. Fellsmere, the inland city west of Sebastian, reached 5,028. On those figures Sebastian holds roughly one in six county residents and more people than any other incorporated place in the county.

Area tells a similar story. The Census Bureau 2024 Gazetteer lists Sebastian city with 17.4 square miles of land and 0.817 square miles of water, centered near 27.78 degrees north and 80.48 degrees west. That land includes the Sebastian Highlands neighborhoods west of U.S. 1 and the Sebastian Municipal Airport. The City of Sebastian describes that airport as a small general aviation field in the north coastal region of Indian River County, built by the U.S. Navy in 1943 as Roseland Satellite Field.

Sebastian sits in Indian River County Commission District 2, one of five districts on the county's Board of County Commissioners.

Indian River County is governed by a five-member Board of County Commissioners. As of October 10, 2026, the county commission page lists Joseph E. Flescher as the District 2 commissioner. Sebastian Daily reported on August 6, 2026 that the District 2 seat covers much of northern Indian River County, including Sebastian, that the five-term commissioner is not seeking reelection, and that the Republican nominee from the August 18 primary faces a Democrat in the November 3, 2026 general election.

The county commission sets the county share of the property tax bill on every Sebastian home and runs county roads and parks, including the county beach parks on Orchid Island east of the city. The Sebastian City Council, elected separately, governs the services that belong to the city inside its limits.

Last verified: October 10, 2026, on the Indian River County website.