This category is for mathematicians who held the nationality of undivided Korea. Typically, this includes people who published or taught during periods such as Korea under Japanese rule (1910–1945), the Korean Empire (1897–1910), the Joseon Dynasty (1392–1897), or earlier.

People of the Korean peninsula who published or taught after 1948 generally do not belong in this category. Instead, they should be placed in the subcategories Category:North Korean mathematicians or Category:South Korean mathematicians based on their nationality, place of origin, or place of residence. However, Korean people living abroad who never had any national affiliation to either North or South Korea (such as Koreans in Japan who never declared a change of nationality from Chōsen-seki), or whose nationality is not publicly known, should remain in this category. Use common sense when determining whether individuals who published or taught between 1945 and 1948 should belong in this category or the North or South Korean subcategories.