According to the 2011 census Kottayam district has a population of 1,979,384, roughly equal to the nation of Slovenia or the US state of New Mexico. This gives it a ranking of 234th in India (out of a total of 640). The district has a population density of 896 inhabitants per square kilometre (2,320/sq mi). Its population growth rate over the decade 2001–11 was 1.32%. Kottayam has a sex ratio of 1040 females for every 1000 males, and a literacy rate of 96.4%.
As per 2001 Indian Census, population in Kottayam includes Hindus (49.32%), Christians (44.60%) and Muslims (5.97%).
Hindus, Christians and Muslims form a significant part of the population. In 2001 Indian Census Muslim Population is 5.97%, Hindu 49.32%, Christian 44.60%. Kottayam, Thiruvalla and Chengannur are the railway stations for pilgrims heading to the Hindu holy site of Sabarimala.
Kottayam is a major center for Syrian Christians in Kerala. Syrian Christians include Malankara Orthodox, Jacobite Syrian Christian Church (Jacobite), Knanaya, Syro-Malankara Catholic, Malankara Marthoma, and other members of Syro-Malabar Catholic and Madhya Kerala Diocese of the Church of South India. About 40% of Kottayam Christians are Orthodox Christians[ Malankara Orthodox, Jacobite Syrian Christian Church (Jacobite), Knanaya ], 30% are Catholic Christians [ Syro-Malankara Catholic, Knanaya ] and remaining 30% are Protestants. Catholic Church had the highest population among different Christian Denominations with over 500,000 population including Roman Catholic, Knanaya Catholic and Malankara Catholic. Malankara Orthodox Church with over 350,000 and Jacobite Church with its nearly 200,000 population including Jacobite Knanaya population. Among Protestant's CSI church is the largest denomination in the district with over 15,0000 believers. Protestants in Kottayam include Pentecost churches. A number of old and sacred Christian churches are also located in Kottayam.
Saint Alphonsa, first canonised saint of the Syro-Malabar Catholic ChurchK R Narayanan, the former President of IndiaOommen Chandy, the former Chief minister of KeralaMammootty, noted as one of the greatest actors that Indian cinema has ever produced.Dulquer Salmaan, prominent stylish youth icon of MollywoodMannathu Padmanabhan, famous social reformer and the founder of Nair Service Society (N.S.S.)K.M. Mani, ex-minister of finance, KeralaVaikom Muhammad Basheer, one of the best writer that world has ever produced.P. K. Narayana Panicker, N.S.S General SecretaryMar Joseph Powathil, Archbishop Emeritus Archdiocese of ChanganacherryMar Joseph Perumthottam, Archbishop Archdiocese of ChanganacherryMannathu Padmanabhan, Founder of Nair Service Society (N.S.S.)Thiruvanchoor Radhakrishnan, the transport minister of KeralaA. R. Raja Raja Varma (Rajaraja Varma Koyi Thampuran (1863–1918), who is known as Kerala Panini. He was a poet, grammatician and professor of Oriental LanguagesKerala Varma Valiya Koil Thampuran (Valiya Koilthampuran) (1845–1919), who was a Malayalam-language poet and translator.Janardhanan, a famous actor in IndiaKPAC Lalitha, a famous South Indian actressGuinness Pakru, a South Indian actor who is the shortest actor in the worldMiss Kumari, a Malayalam film actress of the early years of 1940–1960sRimi Tomy, a famous playback singer in KeralaPonkunnam Varkey, a famous Malayalam writerManoj K. Jayan, a famous Malayalam actorArundhati Roy, an Indian author and political activistSanthosh George Kulangara, the Producer of the famous TV series SancharamUlloor S. Parameswara Iyer, one of the famous poets in IndiaParvathy Omanakuttan, the Miss World 2008 runner-upJose Prakash, a famous Malayalam actorBabu Antony a South Indian actorP. C. George, incumbent MLA from PoonjarAlphons Kannanthanam, the famous beureaucrat-turned-politician who was elected to the Kerala Legislative Assembly in 2006 from KanjirappallyBeena Kannan, the managing director and lead designer of Seematti SilksAnju Bobby George, a famous Indian athleteJoseph Abraham, a famous Indian athlete who won a gold medal in Guangzhou Asian Games 2010Kottayam Nazeer, a mimicry artist and also a movie actorKottayam Pushpanath, a Malayali author who is known for his detective novelsHakim an actor and director of Malayalam cinema industryBheeman Raghu, an actor of KeralaP. C. Devassia, a writer of KeralaK. G. Balakrishnan, the first judge from the state of Kerala to become the Chief Justice of the Supreme CourtPala Narayanan Nair, an Indian poetM. M. Jacob, an Indian politicianP. C. Chacko, the Member of Parliament from Thrissur Lok Sabha seat in KeralaP. J. Sebastian, an Indian freedom fighterSaint Alphonsa, a Syro-Malabar Catholic Franciscan religious sister who is now honored as a saintJanaki Ramachandran, a Tamil actress and politicianKottarathil Sankunni, an author of Malayalam literatureListin Stephen, an Indian film producer known for his Malayalam filmsAnto Antony, a newly elected member of the 15th Lok Sabha from the Pathanamthitta electoral district in KeralaGeethu Anna Jose, an Indian basketball player who has been the captain of the Indian women's national basketball teamMonce Joseph, an MLA and an advocate, he was the youngest minister in Kerala's last LDF ministryM. K. Kamalam, an actress in Malayalam cinema. She was the heroine in the first Malayalam talkie film, Balan (1938)P. K. Vasudevan Nair was the 9th Chief Minister of Kerala and a senior leader of the Communist Party of India (CPI)Martin Prakkat renowned Malayalam film director and photographerAlex Thomas renowned English art director in States