Luck (幸運 Kōun) is a stat whose tooltip often describes it as a measurement of the divine favor a character has, or some variant thereof. In most games, 1 point in Luck will increase both hit rate and evasion by 1, and reduce enemy critical hit rates by 1. In most games where a Devil Axe exists, 1 Luck will also reduce the backfire chance by 1%. On desert maps where objects lie in the sand, Luck sometimes affects the ability to unearth them. In most games, enemy units have very low Luck compared to player-controlled units. Luck can be increased by the means of a Goddess Icon.

In Fire Emblem: Shadow Dragon, the effects of Luck on hit rate and evasion are halved. In Fire Emblem: Genealogy of the Holy War, Ulir blood gives a 30% boost to luck growth. Baldur and Blaggi blood give a 10% boost to luck growth. In Fire Emblem Awakening, Luck is used for calculating the activation rates of Miracle, Despoil, and Armsthrift. In Fire Emblem Fates, Luck is used for calculating the activation rates of Dragon Ward, Salvage Blow, MiracleProfiteer, Good Fortune, and Witch's Brew, as well as the activation rates of the personal skills of Kaze, Keaton, Velouria, and Anna.