Gules, a rock Argent within a garland of oak leaves and acorns Proper within a bordure of the second.
On a wreath of the colors Argent and Gules a mythological chinze (Burmese lion) sejant of the first gorged with a mural crown Azure surmounting a grove of bamboo Vert the top arched above the chinze and the base between four billets, two and two, Or each charged with three barrulets of the second.
OMNES RES BENE FACERE (To Do All Things Well).
The shield is red for Engineers. The rock, taken from the Arms of St. Mihiel and the oak leaves emblematic of the Meuse-Argonne, indicate the service of the 37th Engineer Regiment in World War I, while the border indicates descent of the 209th Engineer Battalion from the 37th Engineer Regiment. The motto translates to "To Do All Things Well."
The unit's World War II campaign service for which it was awarded the Presidential Unit Citation (Army), MYITKYINA, is denoted by the mythological chinze from the Burma State Seal and the blue mural crown of Myitkyina, the heavily fortified town in north Burma, the capture of which was vital in breaking the land blockade of China; blue is the color of the Presidential Unit Citation (Army) streamer. The bamboo grove from the coat of arms of the Republic of Vietnam represents Vietnam campaign service and together with the four billets (heraldic bricks) in colors suggested by the flag of the Republic of Vietnam refers to the battalion's five Vietnam decorations (4 Meritorious Unit Commendations, VIETNAM, and Republic of Vietnam Civil Actions Medal).
The coat of arms was originally approved for the 209th Engineer Battalion on 15 February 1945. It was redesignated for the 27th Engineer Combat Battalion on 19 March 1951. The insignia was redesignated for the 27th Engineer Battalion (Combat) on 15 July 1955. The coat of arms was redesignated and amended to add a crest for the 27th Engineer Battalion on 23 November 1973.