He demonstrated an outstanding ability in management of his own territory as well as in outward military expeditions, and he succeeded in transforming the head of the Imagawa clan into a Sengoku daimyo, expanding his territory from Suruga Province, Totomi Province and Higashimikawa (eastern part of Mikawa Province) to Nishimikawa (west part of Mikawa Province), even reaching into a part of Owari Province.
領国経営と外征の双方に才能を発揮し、今川氏の戦国大名への転身を成功させ、所領も駿河・遠江国・東三河から、西三河や尾張国の一部にまで拡大した。