As a result of successive waves of migration over the course of several centuries, the population of the city is a mix of people from all parts of Kerala and most of India. The pan-Indian nature is highlighted by the substantial presence of various ethnic communities from different parts of the country. Kochi has a diverse, multicultural, and secular community consisting of Hindus, Christians, Muslims, Jains, Sikhs, and Buddhists among other denominations, all living in peaceful co-existence. The Head of the Syro-Malabar Church has his seat at Ernakulam. The city once had a large Jewish community, known as the Malabar Yehuden—and now increasingly as Cochin Jews—that figured prominently in Kochi's business and economic strata. Appropriate to its multi-ethnic composition, Kochi celebrates traditional Kerala festivals like Onam and Vishu along with North Indian Hindu festivals like Holi and Diwali with great fervour. Christian and Islamic festivals like Christmas, Easter, Eid ul-Fitr and Milad-e-sherif are also celebrated. A merry making fest called the Cochin Carnival is celebrated at Fort Kochi during the last ten days of December.

Residents of Kochi are known as Kochiites; they are an important part of the South Indian weltanschauung. However, the city's culture is rapidly evolving, with Kochiites generally becoming more cosmopolitan in their outlook. The people are also increasingly fashion-conscious, often deviating from the traditional Kerala wear to western clothing.

The old Jewish synagogue in Kochi
Kochiites generally partake of Keralite cuisine, which is generally characterised by an abundance of coconut and spices. Other South Indian cuisines, as well as Chinese and North Indian cuisines are popular. Fast food culture is also very prominent.

Kochi was home to some of the most influential figures in Malayalam literature, including Changampuzha Krishna Pillai, Kesari Balakrishna Pillai, G. Sankara Kurup, and Vyloppilli Sreedhara Menon. Prominent social reformers such as Sahodaran Ayyappan and Pandit Karuppan also are from Kochi.

Kochiites are known for their enthusiasm in sports, especially cricket and football. The Jawaharlal Nehru International Stadium in Kochi is one of the largest multi-use stadiums in India. The Regional Sports Centre is an important centre of sporting activity in the city.