The temple is dedicated to the bodhisattva Kannon, also known as Guan Yin or the Goddess of Mercy. According to legend, a statue of the Kannon was found in the Sumida River in 628 by two fishermen, the brothers Hinokuma Hamanari and Hinokuma Takenari. The chief of their village, Hajino Nakamoto, recognized the sanctity of the statue and enshrined it by remodeling his own house into a small temple in Asakusa, so that the villagers could worship the Kannon.
The first temple was built on the site in 645, which makes it the oldest temple in Tokyo. In the early years of the Tokugawa shogunate, Tokugawa Ieyasu designated Sensō-ji as tutelary temple of the Tokugawa clan.
During World War II, the temple was bombed and for the most part destroyed. It was rebuilt later and is a symbol of rebirth and peace to the Japanese people. In the courtyard there is a tree that was hit by a bomb in the air raids, it had regrown in the husk of the old tree and is a similar symbol to the temple itself.
Sensō-ji is the focus of Tokyo's largest and most popular matsuri (Shinto festival), Sanja Matsuri. This takes place over 3–4 days in late spring, and sees the surrounding streets closed to traffic from dawn until late evening.
Many tourists, both Japanese and from abroad, visit Sensō-ji every year. Catering to the visiting crowds, the surrounding area has many traditional shops and eating places that feature traditional dishes (hand-made noodles, sushi, tempura, etc.). Nakamise-Dori, the street leading from the Thunder Gate to the temple itself, is lined with small shops selling souvenirs ranging from fans, ukiyo-e (woodblock prints), kimono and other robes, Buddhist scrolls, traditional sweets, to Godzilla toys, t-shirts, and cell-phone straps. These shops themselves are part of a living tradition of selling to pilgrims who walked to Sensō-ji.
Within the temple itself, and also at many places on its approach, there are omikuji stalls. For a suggested donation of 100 yen, visitors may consult the oracle and divine answers to their questions. Querents shake labelled sticks from enclosed metal containers and read the corresponding answers they retrieve from one of 100 possible drawers.
Within the temple is a quiet contemplative garden kept in the distinctive Japanese style.
The length of the street is approximately 250 meters and contains around 89 shops.