Osbourn High School traces its origins back over 100 years to the private Manassas Institute. In 1890, Miss Eugenia H. Osbourn came to Manassas and was named assistant principal of the institute. Her sister, Fannie Osbourn, was the principal at the time. Through the hard work and dedication of this sister team, the school’s reputation grew. By 1898, graduates were routinely admitted to colleges and universities, a testament to the high standards of education set by the Osbourns.

In 1908, the Manassas Institute became part of the Virginia Public School System and the institute was renamed the Manassas Agricultural High School. Miss Eugenia Osbourn was named principal when her sister, now Mrs. Fannie Osbourn Metz, passed away in 1912. In 1928, a new high school building was erected on Lee Avenue and was named Manassas High School. Miss Eugenia was principal until she retired in 1935. In 1939, to honor Miss Eugenia, the high school was renamed Osbourn High School. Miss Eugenia stayed on as the school’s librarian until 1943 and passed away in 1951. 

The building on Lee Avenue housed Osbourn High School until the fall of 1953, when a new school opened on Tudor Lane. By the early 70s, the Tudor Lane building had become too small, despite additions, to house the growing high school age population of Manassas and surrounding Prince William County. In 1975, Prince William County Public Schools closed the building on Tudor Lane and students began attending a newly constructed school building on Euclid Avenue between Manassas and Manassas Park in Prince William County. The building had Osbourn Park High School (OPHS) displayed on its facade. In the fall of 1975, the Osbourn Yellow Jackets became the Osbourn Park Yellow Jackets and the royal blue and gold of OHS now belonged to OPHS.

The year 1975 also marked the year Manassas dropped its town status and became a city. Shortly thereafter, Manassas City decided to start its own school system. The city bought three old school buildings from Prince William County and renovated them (Baldwin, Dean, and Osbourn).  In the fall of 1977, the building at 9005 Tudor Lane reopened as Osbourn High School housing grades 9-12, Mr. Victor Egidi was the principal and Mr. L.A. Rorrer Jr. was his assistant. The eagle was chosen as the school mascot; navy blue and silver gray became the school colors. The rest, as they say, is history.

In an effort to accommodate increasing enrollment due to the city’s rapid growth, portable classrooms (i.e., trailers) graced the front lawn of OHS and additions were constructed a number of times during the 1980s.  When Grace E. Metz Junior High School opened in the fall of 1990, Osbourn became a three-year secondary school for grades 10 through 12. Enrollment continued to grow throughout the 1990s, and the building became severely overcrowded. Classroom trailers returned to the front lawn and the sections of the school built in the 1950s and 60s were deteriorating badly. The decision was made to raze all parts of the school except for the additions built in the early and mid-1980s. A new building would be constructed adjacent to and surrounding the portions that were to remain. The science wing from the 1980s was renovated to house the Johnson Learning Center, the school division’s alternative education school.  

On November 8, 1999, the students and staff moved only a few feet from the old Osbourn to the new Osbourn. The old Osbourn was subsequently reduced to rubble and hauled away.  In September 2000, the “graduated” eighth graders from Metz moved to Osbourn. The 9-12 grade level structure was restored, and the first ninth graders to walk the halls of Osbourn in 10 years became the Osbourn High School graduating class of 2004. 

The Johnson Learning Center, which previously housed the school division’s alternative education school, is once again part of the high school and is now connected to the main building by a breezeway. The newly-renovated and renamed Joseph B. Johsnon Wing reopened in 2014, providing an additional 10 classrooms for the city's sole high school to host both traditional courses and non- traditional education courses.