The precocious son of a symphony double bass player, Okko Kamu began his formal studies at age six. Initially a violinist, he later turned to conducting and subsequently found himself the center of world attention after winning first prize in the first Herbert von Karajan International Competition. Kamu's preparation had been thorough enough to permit him to impress colleagues, critics, and audiences in the numerous engagements that followed. Since then, he has held several significant appointments, winning special approval for performances and recordings of Scandinavian music. After studies with Onni Suhonen at the Sibelius Academy, Kamu joined the Helsinki Youth Orchestra. At age 19, he joined the Helsinki Philharmonic Orchestra as assistant principal of the second violins. A year later, he was appointed concertmaster of the Finnish Opera Orchestra and during his two years there (1966 to 1968), functioned as third conductor. Despite having had no formal podium training, Kamu took the top prize in the first Karajan conducting competition in 1969; he was just 23 years old. A spate of guest engagements followed for the next two years and Kamu traveled to venues in Europe, America, and the Far East. From 1971 to 1977, Kamu held the position of chief conductor of the Finnish Radio Orchestra. Overlapping that appointment was his engagement as artistic director and chief conductor of the Oslo Philharmonic from 1975 to 1979. In 1981, Kamu began an eight-year engagement as music director of the Helsinki Philharmonic, concurrently serving as music director of the Netherlands Royal Symphony Orchestra from 1983 to 1986. In 1988, Kamu became principal conductor of the Sjaellands Symphony Orchestra in Copenhagen and served the Helsingborg Symphony Orchestra as principal conductor beginning in 1991. From 1998 to 2001, Kamu was principal guest conductor of the Lausanne Chamber Orchestra. Immediately after his success in the Karajan competition, Kamu began to record and remained a frequent presence in the recording studio. Among his earlier discs of lasting significance are the Sibelius First and Third symphonies. He has made noteworthy recordings of Berwald, Grieg (Symphony in C minor), and Sallinen. Kamu also led the premieres of Sallinen's The Red Line (1978) and The King Goes Forth to France (1984).
In 2009, he was named the chief conductor of the Lahti Symphony Orchestra and his recorded efforts were rewarded with the Diapson D'Or award for two Naxos discs of Berwald's works.