He was born in the village of Staraya Maina, Ulyanovsk region, and soon the family moved to Siberia. The writer spent his childhood in the village of Malozorkaltsevo, Tobolsk district. In 1941, Konstantin graduated from Golyshman secondary school. His career began in July 1941. At first he worked as an educator, then as the director of the Golyshman orphanage, and in the autumn of 1942 he became a professional Komsomol worker and stayed in this capacity for fourteen years. In 1950, he graduated from the History Department of Tyumen University, in 1958 — postgraduate studies at the Tajik University — received the degree of Candidate of Historical Sciences.
Since 1952, he began his literary activity. A number of works were published under the pseudonym K. Golovan. In 1961 he came to Tyumen. He worked as the editor-in-chief of the Tyumen Book Publishing house. In 1959, he was admitted to the Union of Writers of the USSR. In 1963, through his efforts, the Tyumen Regional Writers' Organization was created, which K.Ya. Lagunov headed for twenty years (1963−1983). In 1988, he organized the creation of a journalism department at Tyumen State University, headed the corresponding department. Lagunov was engaged in mentoring and promoting the work of young authors at the University. Konstantin Yakovlevich created the project "Signs of the XX century" with students of the journalism department of TSU in the late 1990s — early 2000s. This literary series consists of ten books that can be called artistic chronicles of their time. He died in Tyumen on July 19, 2001.
Over forty-three years of literary activity, Konstantin Yakovlevich has written and published more than fifty books, including 12 novels, Many of the writer’s works have been translated into foreign languages. The creative range of the writer is amazing: from screenplays to children’s fairy tales. He worked a lot and successfully in the genres of journalism.
He was awarded twice (1954,1967) the Order of the Badge of Honor (1954), the Order of Friendship of Peoples (1967). Honored Worker of Culture of the RSFSR (1995). Honorary citizen of the city of Tyumen (1994).