The shield has a green background. In its upper half there is a cross flordelisada that is divided by a vertical line, another horizontal one and the diagonals, between which they appear alternated the silver and black colors. In the lower part of the shield, there is the design of a strong house with its walls crowned with battlements. The strong house has a small coat of arms over the door with the drawing of a lion raised on its hind legs. The insignia that has been placed on the coat of arms is a crown formed by walls and towers. The flordelisado cross, which is the insignia of the Order of Preachers of Santo Domingo, represents San Pedro Mártir de Verona, Patron Saint of the City of Guaynabo. 

The strong house symbolizes the town of Caparra, the primitive capital of Puerto Rico, whose ruins are preserved as a historical treasure in the territory of Guaynabo. It represents the residential house of the conquistador Juan Ponce de León, which in addition to serving as a dwelling for the first governor of Puerto Rico and his family, served as the seat of our oldest municipal council. It was also the first fortress of the island. The coat of arms above the door is the coat of arms of the Ponce de León family. The green and silver colors have been chosen as the main colors of the coat of arms because they are the oldest heraldic colors of Guaynabo.