Porto-Novo (Portuguese for 'New Port', Portuguese pronunciation: [ˈpoɾtu ˈnovu], French pronunciation: [pɔʁtɔnɔvo]; Yoruba: Àjàṣẹ́; Fon: Xɔ̀gbónù; also known as Hogbonu and Ajashe) is the capital and second-largest city of Benin. The commune covers an area of 52 square kilometres (20 sq mi) and as of 2002 had a population of 223,552 people.

In 1863, following British bombardment, Porto-Novo accepted French protection, and by 1900, it became the capital of French Dahomey. After Benin's independence in 1960, Porto-Novo retained its status as the official capital, while Cotonou emerged as the economic and administrative hub.

Situated on an inlet of the Gulf of Guinea, in the southeastern portion of the country, the city was originally developed as a port for the transatlantic slave trade led by the Portuguese Empire. It is Benin's second-largest city, and although it is the official capital, where the national legislature sits, the larger city of Cotonou is the seat of government, where most of the government buildings are situated and government departments operate.

The name Porto-Novo is of Portuguese origin, literally meaning "New Port". It remains untranslated in French, the national language of Benin.

Porto-Novo was once a tributary of the Yoruba Oyo Empire, which had offered it protection from the neighbouring Fon, who were expanding their influence and power in the region. Today, the Yoruba community in Porto-Novo remains one of the two original ethnic groups in the city. The city was originally called Ajashe (Àjàṣẹ́ in Yoruba orthography) by the Yorubas, and Hogbonu by the Gun.^{[citation needed]}

Although historically the original inhabitants of the area were Yoruba speaking, there seems to have been a wave of migration from the region of Allada further west in the 1600s, which brought Te-Agbalin (or Tê-Agbanlin) and his group to the region of Ajashe in the late 16th century. ^{[citation needed]}

In 1730, the Portuguese Eucaristo de Campos named the city "Porto-Novo." Although colonizers claim the name was due to its resemblance to the city of Porto, the real reason was to signal the development of a new port for the slave trade.

In 1861, the British, who were active in nearby Nigeria, bombarded the city, which caused the Kingdom of Porto-Novo to accept the French offer of protection in 1863. The neighbouring Kingdom of Dahomey objected to French involvement in the region and war broke out between the two states. In 1883, Porto-Novo was incorporated into the French "colony of Dahomey and its dependencies" and in 1900, it became Dahomey's capital city. As a consequence, the city’s inhabitants, who previously spoke local languages, began to adopt French alongside them, with the addition of French to the language repertoire of the city's inhabitants.^{[citation needed]} Unlike the city's earlier Gun migrants, however, the French sought to impose their language in all spheres of life and completely stamp out the use and proliferation of indigenous languages.^{[citation needed]}