Chemplast Sanmar Limited is an Indian chemical company. It is a major manufacturer of PVC resins, chlorochemicals and piping systems.

The company was formed in 1962 to manufacture PVC resins/compounds and fabricate PVC products. In 1967 a PVC Plant at Mettur was commissioned with a capacity of 6,000 TPA, in collaboration with BF Goodrich. PVC pipes production commenced. It was among the pioneers to bring PVC pipes to India.^{[citation needed]}

In 1985 the company acquired a controlling stake of Mettur Chemical & Industrial Corporation (MCIC) Ltd.^{[citation needed]}

The Cuddalore PVC project was commissioned in September 2009.

In August 2021, Chemplast Sanmar opened its initial public offering at a price band of ₹ 530-541 per share.

Chemplast Sanmar Limited is part of Sanmar Group which has businesses in Chemicals, Shipping, Engineering and Metals. It has a turnover of over ₹ 65 billion and a presence in some 25 businesses, with manufacturing units spread over numerous locations in India.

Chemplast Sanmar's manufacturing facilities are located at Mettur, Panruti, Cuddalore and Ponneri in Tamil Nadu, Shinoli in Maharashtra, and Karaikal in the Union Territory of Puducherry.

Cuddalore PCV is the largest such project in Tamil Nadu. Its aggregate capacity of 235,000 tons makes it one of India's largest PVC players.