Ōtsu is the capital city of Shiga Prefecture, Japan

Ōtsu may also refer to:

Ōtsu Station, a railway station in Ōtsu, Shiga, Japan Ōtsu District, Yamaguchi, a former district in Yamaguchi Prefecture, Japan Ōtsu (surname), a Japanese surname Ōtsu-juku, a station of the Nakasendō and the Tōkaidō Otsu, a variant of the Type 89 I-Go medium tank