The flag of Colorado was officially adopted to represent the U.S. state of Colorado on June 5, 1911. The flag, designed by Andrew Carlisle Carson, consists of a fess design of three horizontal stripes of equal width, with the top and bottom stripes colored blue, and the middle stripe colored white. A circular red "C", filled with a golden disk, sits atop the stripes. All aspects of the flag contain symbolism related to the state, as the blue is meant to represent the sky, the gold the abundant sunshine the state receives, the white the snowcapped Rocky Mountains, and the red the "ruddy" earth. The gold and white portions of the flag also represent the state's gold and silver mining industries, respectively.

The state had one previous official flag before the current one, from 1907 to 1911. The Denver chapter of the Daughters of the American Revolution, unaware that this flag existed, wanted to create a flag for the state and settled on a red and white colored one, designed with the help of then-state senator William H. Sharpley. This flag was presented to the legislature but, because it was less popular than Carson's design, it was replaced. The new design passed the Senate and House of Representatives on April 25 and May 6, 1911, respectively. The flag made its public debut at a parade on May 30, 1911, and was officially adopted on June 5, 1911. Further revisions were made by the legislature on February 28, 1929, to specify the exact colors used and on March 31, 1964, to specify the size and positioning of the letter "C" and gold disk.