A gold color metal and enamel device 1 5/16 inches (3.33 cm) in height overall consisting of a crimson flame surmounted by a blue equilateral triangle charged in center with a gold eight-rayed sun above two gold bolo knives in saltire overall. Attached below the bolo handles a gold triparted scroll inscribed "FIRST IN MAINTENANCE" in blue letters.
The crimson flame alludes to the parent unit's origin as an Ordnance Battalion. The crossed bolo knives represent campaign honors earned in Luzon and New Guinea by the predecessor during World War II. The golden sunburst on the blue triangle is adapted from the flag of the Philippines and denotes the award of the Presidential Unit Citation to the former unit.
The distinctive unit insignia was originally approved for the 189th Maintenance Battalion on 15 March 1967. It was redesignated for the 189th Support Battalion with the description and symbolism revised effective 16 September 1993.