Shingū is located near the southern tip of Wakayama Prefecture on the Kii Peninsula, on the west side of the mouth of the Kumano River.

Shingū has a Humid subtropical climate (Köppen Cfa) characterized by warm summers and cool winters with light to no snowfall.

After the Meiji restoration, the area became part of the Higashimuro District, Wakayama, and the town of Shingū was established with the creation of the modern municipalities system on April 1, 1889.

On October 1, 2005, the town of Kumanogawa (from Higashimuro District), an exclave between Nara and Mie prefectures, was merged with Shingū.

In terms of national politics, the city is part of Wakayama 3rd district of the lower house of the Diet of Japan.

Primary industries include forestry, commercial fishing, growing of leafy vegetables such as komatsuna and horticulture, and "Kumano brand" beef.