A deck light assembly for attachment to a deck railing includes a C-shaped body with a core nesting within a cover and a top plate extending between two legs. A foot extends inwardly from each of the legs to engage the bottom of the deck railing and secure the deck light assembly thereon. A solar panel on the top plate charges a battery and causes an LED light to illuminate in the absence of ambient light. A shade on the outer surface of one of the legs directs light downwardly. One leg includes a catch with a planar portion biased inwardly to engage the deck railing and configured to flex outwardly to disengage from the deck railing. A nub extends from the catch for application of an outward force to flex the planar portion for attaching or removing the deck light assembly from the deck railing.