Seffner is a census-designated place (CDP) in Hillsborough County, Florida, United States. The population at the 2020 census was 8,362, up from 7,579 at the 2010 census.

Located approximately 13 miles (21 km) east of downtown Tampa, Seffner is considered a suburb. Though still characterized by towering live oak trees, strawberry farms and lakes, Seffner has been growing rapidly in recent years, with housing subdivisions being added to the once rural landscape.

Some historians claim that Seffner's streets were originally laid out in 1862, but not recorded as a plat formally until 1885. Seffner's post office opened in 1884, when a new railroad line in the area had been planned. The community was named for its first postmaster, Frederick P. Seffner. That same year, Seffner's first school and store were opened. Seffner quickly became a prosperous small community with citrus groves, a hotel, one drug store, several dry goods stores, and a livery stable. When an epidemic of yellow fever hit Tampa in the fall of 1887 and in 1888, many Tampa refugees fled to Seffner for temporary shelter in the hotel. However, as refugees and mail arrived in Seffner, they were fumigated as protection from the epidemic. Among the refugees was T.C. Taliaferro of the First National Bank of Tampa, who operated a branch banking business from Seffner during the epidemic.

The main thoroughfare leading north and south was Lenna Avenue, and leading east and west was Highway Number 23, renamed Buffalo Avenue, because of its erstwhile use as a buffalo trail, and then renamed again in 1989 to its current name, Dr. Martin Luther King Jr. Boulevard (Hwy 574). Seffner and neighboring Mango and Dover served as the three primary towns along the South Florida Railroad right-of-way between Tampa and Plant City. These towns owe their existence and prosperity to the railroad, each becoming an important shipping center.

The cold in the winter of 1894–1895 brought disaster to Seffner. Many citizens left, while others remained to recoup their losses. Seffner survived and eventually regained its affluence. Attractive residential neighborhoods were built to accommodate the influx of desirable residents. By 1925, Seffner was the fourth-largest town in Hillsborough County.

Seffner is located northeast of the center of Hillsborough County and is bordered by Thonotosassa to the north, Mango to the west, and Brandon to the south. Interstate 4 is the northern boundary of the CDP, and the southern boundary follows State Road 574 (Dr. Martin Luther King Jr. Boulevard). Plant City is 10 miles (16 km) to the east.

The Seffner CDP has a total area of 3.8 square miles (9.8 km), of which 3.6 square miles (9.3 km) are land and 0.2 square miles (0.5 km), or 5.34%, are water, according to the United States Census Bureau.

Historical population

Census	Pop.	Note	%±
1990	5,371		—
2000	5,467		1.8%
2010	7,579		38.6%
2020	8,362		10.3%
source:

As of the census of 2000, there were 5,467 people, 2,075 households, and 1,520 families residing in the community. The population density was 1,512.2 inhabitants per square mile (583.9/km). There were 2,168 housing units at an average density of 599.7 units per square mile (231.5 units/km). The racial makeup of the community was 91.35% White, 3.26% African American, 0.29% Native American, 1.02% Asian, 2.71% from other races, and 1.37% from two or more races. Hispanics or Latinos of any race were 8.21% of the population.

There were 2,075 households, out of which 34.9% had children under the age of 18 living with them, 56.1% were married couples living together, 11.7% had a female householder with no husband present, and 26.7% were non-families. 21.5% of all households were made up of individuals, and 8.9% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.04.

In the community the population was spread out, with 26.4% under the age of 18, 7.7% from 18 to 24, 29.9% from 25 to 44, 24.4% from 45 to 64, and 11.6% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 95.4 males. For every 100 females age 18 and over, there were 90.0 males.

The median income for a household in the community was $42,614, and the median income for a family was $49,152. Males had a median income of $32,266 versus $26,328 for females. The per capita income for the community was $19,888. About 3.2% of families and 4.6% of the population were below the poverty line, including 4.0% of those under age 18 and 7.5% of those age 65 or over.

The Seffner-Mango Branch Library is located in Seffner.

There are six public parks in Seffner: Seffner-Mango Park, Evans Recreation Center, E.L. Bing Park, Higginbotham Park, Mango Dog Park, and Lakewood Park.

Lake Weeks is a lake located on the southeast side of Seffner. It has a surface area of 57.73 acres and is known for its fishing and Spanish moss.

Three recreation centers are located in Seffner. The Evans Recreation Center offers special programs for children ages 6–17 and it features a basketball court, playground equipment, a hockey court, a softball field, a football field, and a soccer field. The Mango Recreation Center has a large park with two basketball courts, two softball fields, a playground, and a 5-acre dog park. The Seffner Civic Center is a historical land site with a basketball court, picnic tables, a playground, and a large open field.

The Rodney Colson Sports Complex is a park with an open field, biking trail, and walking trail.

The Life Fellowship Bird Sanctuary located in Seffner, affiliated with a local church. Birds and reptiles are kept there, and the facility is noted for its success in breeding rock iguanas in captivity.

Hillsborough County Public Schools serves Seffner.

• Colson Elementary
• Lopez Elementary
• McDonald Elementary
• Seffner Elementary

Pruner elementary

• Gordon Burnett Middle School
• Jennings Middle School

• Armwood High School

• Hillsborough Baptist
• Impact Academy
• Legacy Christian Academy
• Livingstone Academy
• Seffner Christian Academy

• Matt Joyce, professional baseball outfielder, raised in Seffner
• Andrew W.K., musician, lived in Seffner in 1999

• Mango-Seffner, Florida, a single census area recorded during the 1980 census

• Greater Seffner Area Chamber of Commerce