India is home to a large variety of wildlife. It is a biodiversity hotspot with various ecosystems ranging from the Himalayas in the north to the evergreen rain forests in the south, the sands of the west to the marshy mangroves of the east. India lies within the Indomalayan realm and is the home to about 7.6% of mammal, 14.7% of amphibian, 6% of bird, 6.2% of reptilian, and 6.2% of flowering plant species. India's forests contain about 500 species of mammals and more than 1300 bird species.

India is one of the most biodiverse regions of the world and include three of the world's 36 biodiversity hotspots – the Western Ghats, the Eastern Himalayas, and the Indo-Burma hotspot. It is one of the 17 megadiverse countries. The country has 12 biosphere reserves and 75 Ramsar sites.

In response to decrease in the numbers of wild animals, human encroachment and poaching activities, the Government of India established a system of national parks and protected areas in 1935, which subsequently expanded. In 1972, India enacted the Wildlife Protection Act of 1972 and Project Tiger to safeguard crucial habitat. Further federal protections were promulgated in the 1980s.

India has about 2,714 endemic lichen species. In 2020, the Lichen Park in India was developed by the Uttarakhand Forest Department in Munsiyari.

Article 48 of the Constitution of India says, "The state shall endeavour to protect and improve the environment and to safeguard the forests and wildlife of the country" and Article 51-A states that "it shall be the duty of every citizen of India to protect and improve the natural environment including forests, lakes, rivers, and wildlife and to have compassion for living creatures." The committee in the Indian Board for Wildlife, in their report, defines wildlife as "the entire natural uncultivated flora and fauna of the country" while the Wildlife Protection Act, 1972 defines it as "any animal, bees, butterflies, crustacea, fish, moths and aquatic or land vegetation which forms part of any habitat."

Despite the various environmental issues, the country still has rich and varied wildlife.

As of 2020, there are 981 protected areas including 106 national parks, 566 wildlife sanctuaries, 97 conservation reserves and 214 community reserves. In addition there are 51 tiger reserves, 18 biosphere reserves and 32 elephant reserves.Hundreds of India's bird species are in serious decline, according to a study spanning over 25 years.In 2020 the Indian government created the world's first sea cucumber reserve in Lakshadweep – Dr KK Mohammed Koya Sea Cucumber Conservation Reserve, the largest marine conservation reserve – Attakoya Thangal Marine Reserve and the first protected area for marine birds in India – PM Sayeed Marine Birds Conservation Reserve.

Gir forest in India has the only surviving population of Asiatic lions in the world. In the late 1960s, there were only about 180 Asiatic lions. There were more than 600 Asiatic lions in Gir National Park in 2018.

Air pollution in India is a serious environmental issue. Of the 30 most polluted cities in the world, 21 were in India in 2019. As per a study based on 2016 data, at least 140 million people in India breathe air that is 10 times or more over the WHO safe limit and 13 of the world's 20 cities with the highest annual levels of air pollution are in India. 51% of the pollution is caused by industrial pollution, 27% by vehicles, 17% by crop burning and 5% by other sources. Air pollution contributes to the premature deaths of 2 million Indians every year. Emissions come from vehicles and industry, whereas in rural areas, much of the pollution stems from biomass burning for cooking and keeping warm. In autumn and spring months, large scale crop residue burning in agriculture fields – a cheaper alternative to mechanical tilling – is a major source of smoke, smog and particulate pollution. India has a low per capita emissions of greenhouse gases but the country as a whole is the third largest greenhouse gas producer after China and the United States. A 2013 study on non-smokers has found that Indians have 30% weaker lung function than Europeans.

The Air (Prevention and Control of Pollution) Act was passed in 1981 to regulate air pollution but has failed to reduce pollution because of poor enforcement of the rules.

In 2015, Government of India, together with IIT Kanpur launched the National Air Quality Index. In 2019, India launched 'The National Clean Air Programme' with tentative national target of 20%-30% reduction in PM2.5 and PM10 concentrations by 2024, considering 2017 as the base year for comparison. It will be rolled out in 102 cities that are considered to have air quality worse than the National Ambient Air Quality Standards. There are other initiatives such as a 1,600-kilometre-long and 5-kilometre-wide The Great Green Wall of Aravalli green ecological corridor along Aravalli range from Gujarat to Delhi which will also connect to Shivalik hill range with planting of 1.35 billion (135 crore) new native trees over 10 years to combat the pollution. In December 2019, IIT Bombay, in partnership with the McKelvey School of Engineering of Washington University in St. Louis, launched the Aerosol and Air Quality Research Facility to study air pollution in India. According to a Lancet study, nearly 1.67 million deaths and an estimated loss of USD 28.8 billion worth of output were India's prices for worsening air pollution in 2019.

Peepal Baba or Swami Prem Parivartan is an environmentalist who along with his team has planted over 20 million trees in 202 districts across 18 states in India. He was born to a doctor of Indian Army on 26 January 1966 in Chandigarh, India. His English teacher inspired him at the age of 11 to plant trees in 1977. He is the founder of Give Me Trees Trust which was later registered as a non-governmental organization in 2011. He took asceticism in 1984 from Osho Rajneesh, who gave him the name "Swami Prem Parivartan".

Jadav "Molai" Payeng (born 31 October 1959) is an environmental activist and forestry worker from Majuli, popularly known as the Forest Man of India. Over the course of several decades, he has planted and tended trees on a sandbar of the river Brahmaputra turning it into a forest reserve. The forest, called Molai forest after him, is located near Kokilamukh of Jorhat, Assam, India and encompasses an area of about 1,360 acres / 550 hectares. In 2015, he was honoured with Padma Shri, the fourth highest civilian award in India. He was born in the indigenous Mising tribe of Assam.

East Kolkata wetlands

In 2018, The Hindu reported that the East Kolkata wetlands, the world's largest organic sewage treatment facility, had been used to organically clean the sewage of Kolkata for several decades through the use of algae. This natural system, in use since the 1930s, was discovered by Dhrubajyoti Ghosh, an ecologist and municipal engineer in the 1970s, while he was working in the region. Ghosh worked for decades to protect the wetlands. It had been a practice in Kolkata, one of the five largest cities in India, for the municipal authorities to pump sewage into shallow ponds (bheris). Under the heat of the tropical sun, algae proliferated in these bheris, converting the sewage into clean water, which in turn was used by villagers to grow paddy and vegetables. This almost 100-year-old system treats 750 million litres of wastewater per day, providing livelihoods for 100,000 people in the vicinity. For his work, Ghosh was included in the UN Global 500 Roll of Honour in 1990 and received the Luc Hoffmann award in 2016.