Seppo is a Finnish male first name. The name originally derives from the word “seppä,” meaning a blacksmith, and in the Kalevala, Ilmarinen is regularly referred to as Seppo Ilmarinen. Especially in Ostrobothnia, Seppo may also be interpreted as a variation of the name Sepeteus. The Finnish Orthodox calendar associates Seppo with Sebastian, although there is no direct connection between the two. Seppo’s name day is celebrated on June 10. Seppo was included in the Finnish almanac in 1929, but it had already appeared in the Finnish calendar in St. Petersburg in 1909. Some common nicknames for Seppo include Sepe, Sedu, Sepi, and Seppu. There is an association of individuals with the name Seppo called “Seppojen yhdistys” in the Kotka area.

According to the data from the Digital and Population Data Services Agency, from the early 1900s to the end of 2019, 47,960 men in Finland were named Seppo. More than half of them were born in the 1940s and 1950s.