A shield-shaped embroidered item, edged with 1/8 inch (.32 cm) White border, blazoned as follows: Azure, on a fess Argent, a bar wavy of the first, over all a panther rampant, facing to sinister Sable, fimbriated of the second. Attached above the shield, a Blue scroll edged with 1/8 inch (.32 cm) White border inscribed MCKINLEY SHS in White letters. The overall dimensions are 3 1/2 inches (8.89 cm) in height and 2 5/8 inches (6.67 cm) in width.

Royal blue and white are the school colors. The panther is the schools mascot representing ferocity, strength, and courage as well as the cadets fierce and winning spirit. The wavy bar alludes to Mississippi River. Blue signifies the students fidelity to school and country. White reflects integrity which, the cadets strive to achieve. Black conveys determination, an attribute the cadets have in their achieving any goal set before them.

The shoulder sleeve insignia was authorized 15 December 2016. (TIOH Drawing Number A-10J-1149)

A Silver color metal and epoxy device 1 1/4 inches (3.18 cm) in height overall consisting of a shield blazoned: Argent (Silver Gray), between a lyre in dexter and a winged foot in sinister Or, a demi torch issuant from base of the second, enflamed Gules; on a chief wavy Azure, a fleur-de-lis of the first. Attached below the shield, a Blue scroll inscribed LOYAL TO THE ROYAL in Silver.

Royal blue and white are the school colors. Blue signifies the cadets devotion to their school and country. White (Silver), reflects perfection, a quality the cadets strive to achieve in all endeavors. Gold portrays honor, a trait the cadets show in their great respect for their school and country. Red personifies passion, a quality the cadets show in their pursuit of athletic and academic excellence. The wavy chief alludes to the Mississippi River. The fleur-de-lis is the official symbol of the state of Louisiana. The lyre is for the schools marching band the Big Blue Machine. The torch emphasizes the high academic standards of the school. The winged foot highlights the schools strong sports programs especially their football team, the McKinley Panthers. The schools motto is Loyal to the Royal.

The shoulder loop insignia was authorized 15 December 2016.