Belgreen is a census-designated place and unincorporated community in Franklin County, Alabama, United States, located nine miles west of Russellville and around 17 miles east of Red Bay on Alabama Highway 24. As of the 2020 census, Belgreen had a population of 170. Belgreen is a small district, composed of a condensed area of residency, the school, and small businesses.

Belgreen was the county seat of Franklin County between 1878 and 1891. A post office was established in 1879, but it was later closed. The Franklin County Career Technical Center is now located on the site where the county courthouse and jail once stood. Due to this, the road between the Career Technical Center and the Science Hall of Belgreen High School is named Jail Springs Road. The courthouse and jail existed on this site after the county seat was moved from Frankfort, which is approximately seven miles north of Belgreen. The courthouse complex existed on the current grounds of the Career Technical Center until it burned and was eventually moved to Russellville.

Belgreen was listed on the 1880 U.S. census at the time it served as Franklin County Seat. It did not appear again until 2010 when it was listed as a census designated place in the 2010 U.S. census.

Any description of Belgreen would be incomplete without a given history of Belgreen High School, which has existed just south of Alabama Highway 24 for over sixty years.

The story of the naming of Belgreen tells of a young lawyer (who would later become a Franklin County Probate Judge) named Richard S. Watkins. Watkins named the town of Belgreen for a young lady named Belle, whom he was courting at the time. Other sources suggest the name was a purely subjective description of the local geography, constructed from the French word "bel", an adjective meaning "beautiful", and "green". At first, the name was spelled "Bellegreen." The spelling was changed over the years to Bellgreen and later to Belgreen as it is today. Another story recounts that a man named Abner Judd named the town for the beautiful woods and green hillsides in the area.

Between 1878 and 1891, the Franklin County seat was located at Belgreen. A courthouse was built there in 1879 on the site of the present campus of Belgreen High School. The courthouse burned in 1890, which prompted the move of the county seat back to Russellville.

In 1878 or 1879, the first school building was constructed of logs. The seats were made of rough split stumps. This building stood near the present-day intersection of AL HWY 24 and AL HWY 187 where Hester's Store (now defunct) once stood. B.R. Fite was the first official principal of the school. The second site of the school was located east of the present site of Belgreen School. Two large rooms were built there in 1881 with a "Woodmen of the World" meeting room overhead. Nate Redwine served as the principal. The school grew rapidly in the early 1900s. There were so many students that some classes were held at the nearby Methodist Church building and in the old jailhouse located nearby.

Credit is given to Mr. and Mrs. John R. Guin for beginning Belgreen High School. They moved to Belgreen in 1902 and lived in the "old jail" building, adjacent to the site of the former courthouse. Mrs. Guin taught school in her living room in their early years at Belgreen, and later on, she also taught in the upstairs room of the jail. She is called the "mother of Belgreen school" for all of the kind things she did for school students and others in the community. Mrs. Guin also served as the postmaster of the town.