Runeberg studied first in the cities of Vaasa and Oulu, later on at Academy of Åbo, where he befriended Johan Vilhelm Snellman and Zacharias Topelius. His studies concentrated mainly on the classical languages of Latin and Greek. From 1837 onwards he lived in Porvoo, where he served as professor of Roman literature in the Gymnasium of Porvoo.
Many of his poems deal with life in rural Finland. The best known of these is Bonden Paavo , (Farmer Paavo, Saarijärven Paavo in Finnish), about a smallholding peasant farmer in the poor parish of Saarijärvi and his determination, "sisu" (guts) and unwavering faith in providence in the face of a harsh climate and years of bad harvests. Each year he mixes double the amount of bark into his bread to stave off starvation and gives what he can to his neighbors.
Runeberg's most famous work is Fänrik Ståls sägner (The Tales of Ensign Stål, Vänrikki Stoolin tarinat in Finnish) written between 1848 and 1860. It is considered the greatest Finnish epic poem outside the native Kalevala tradition and contains tales of the Finnish War of 1808-09 with Russia. In the war, Sweden ignominiously lost Finland, which became a Grand Duchy in the Russian empire. The poem, which is composed episodically, emphasizes the common humanity of all sides in the conflict, while principally lauding the heroism of the Finns. The first poem "Vårt land" (Our Land, Maamme in Finnish) became the Finnish National Anthem. Runeberg is celebrated on 5 February each year.