The fictional world in which the A Song of Ice and Fire novels by George R. R. Martin take place is divided into several continents, known collectively as The Known World.

Most of the story takes place on the continent of Westeros and in a large political entity known as the Seven Kingdoms. Those kingdoms are spread across nine regions: the North, the Iron Islands, the Riverlands, the Vale, the Westerlands, the Stormlands, the Reach, the Crownlands, and Dorne. A massive wall of ice and old magic separates the Seven Kingdoms from the largely unmapped area to the north. The vast continent of Essos is located east of Westeros, across the Narrow Sea. The closest foreign nations to Westeros are the Free Cities, a collection of nine independent city-states along the western edge of Essos. The lands along the southern coastline of Essos are called the Lands of the Summer Sea and include Slaver's Bay and the ruins of Valyria. The latter is the former home of the ancestors of House Targaryen. To the south of Essos are the continents of Sothoryos and Ulthos, which in the narrative are largely unexplored.

The planet experiences erratic seasons of unpredictable duration that can last for many years. At the beginning of A Song of Ice and Fire, Westeros has enjoyed a decade-long summer, and many fear that an even longer and harsher winter will follow.

George R. R. Martin set the Ice and Fire story in an alternative world of Earth, a "secondary world", such as that which J. R. R. Tolkien pioneered with Middle-earth. Martin has also suggested that world may be larger than the real world planet Earth. The Ice and Fire narrative is set in a post-magic world where people no longer believe in supernatural things such as the Others. Although the characters understand the natural aspects of their world, they do not know or understand its magical elements. Religion, though, has a significant role in the life of people, and the characters practice many different religions.