Aoi-ku borders Suruga-ku in the south and Shimizu-ku to the southeast; the west faces Shimada, Fujieda and Kawanehon and its northern tip extends into the border between Nagano Prefecture and Yamanashi Prefecture.

It is the largest ward in Japan in terms of geographic area.

It consists of the area of Shizuoka prior to its merger with Shimizu, north of the Tōkaidō Main Line rail tracks.

The average annual rainfall is 3,258.6 mm (128.29 in) with September as the wettest month.

The temperatures are highest on average in August, at around 22.4 °C (72.3 °F), and lowest in January, at around 1.2 °C (34.2 °F).