The flag of Christmas Island has a blue background with a golden disk at the center, which depicts a green map of the island surrounded by 23 golden rays representing the island's population. The colors are defined in Pantone and CMYK color systems as follows:

• Blue: Pantone 286C / C: 100 M: 60 Y: 0 K: 30
• Gold: Pantone 1235C / C: 0 M: 20 Y: 90 K: 0
• Green: Pantone 356C / C: 60 M: 0 Y: 100 K: 0

The aspect ratio of the flag is 1:2. The diameter of the golden disk is 3/5 of the hoist width, while the radius of each golden ray is equal to 1/15 of the diameter of the golden disk. The centroid of the disk is located at a distance of 3/10 of the hoist length from the left edge of the flag.

The design of the flag was selected in 1986 through a competition, and it was officially adopted on January 26, 2002.