August Theodor Blanche was born in Stockholm, Sweden, the illegitimate child of a servant girl and a priest. His mother eventually married Johan Jacob Blanck, a blacksmith and the boy took his stepfather's name. A brilliant student, in 1838 he obtained a law degree and for a time, worked as a civil servant until taking up journalism. In the early 1840s, he began writing plays for the theater as well as translating plays from foreign languages into Swedish. By the middle of the decade, he was writing novels and short stories of intrigue, all of which met with a great deal of success.
An activist, in 1859 Blanche was elected to the Swedish Parliament where he served until 1866. He died of a heart attack two years later while participating in a public parade in Stockholm.
August Blanche is interred in the Norra begravningsplatsen in Stockholm.