Yahagi may refer to one of the following ships of the Imperial Japanese Navy and the Japan Maritime Self-Defense Force, named after the Yahagi River:
, a ; participated in World War I; demilitarized in 1940 and used as barracks ship Hai Kan No. 12 during World War II; scrapped in 1947 , an ; participated in World War II; sunk by U.S. carrier-based aircraft April 7, 1945 during Operation Ten-Go , a