On a Blue disc shaped embroidered item bearing a White stylized palmetto tree, throughout surmounted of its trunk with a diagonally crossed Yellow rifle and sabre, muzzle and blade up, all within a circular Yellow designation band, with the inscription SENECA above and HIGH SCHOOL below in Blue letters; all within a 1/8 inch (.32 cm) Blue border. The overall diameter is 3 inches (7.62cm).

Navy blue and gold (yellow) are the school colors. The palmetto tree is the state tree of South Carolina and refers to the geographic location of the school. The crossed sabre and rifle represent military training.

The shoulder sleeve insignia was originally authorized 1 April 1986, it is currently being amended to update the manufacturing drawings and to add the ACU color conversions on 14 August 2018. (TIOH Drawing Number A-10J-27)

On a gold metal and epoxied shield shaped device 1 3/16 inches (3.02 cm) in height overall blazoned as follows; Azure, a stylized bobcats face affronte Or, detailed and fimbriated Sable; a chief dancette of the second. Attached below the shield, a semi-circular Black scroll inscribed SENECA BOBCATS in Gold.      

Navy blue and gold (yellow) are the school colors. The bobcat is the schools mascot, symbolizing the cadets vigilance during academic pursuit and military training. The dancette (indented upper section) and the blue upper background alludes to the hilly landscape and the numerous lakes which characterize the location of Seneca High School within Oconee County, South Carolina.