The governing statute is the Indian Contract Act 1872. For an NDA to be enforceable it must meet the general criteria of a valid contract, namely the consent of the parties, a lawful object, and consideration. Section 10 makes an agreement a contract only where there is free consent, lawful consideration and a lawful object; Section 11 fixes capacity, so an NDA signed by a minor is void. There is no separate statute dedicated to confidentiality in India, which means the entire enforceability question is decided under contract law and the equitable doctrine of breach of confidence.
The provision that shapes every NDA is Section 27. It declares that every agreement by which anyone is restrained from exercising a lawful profession, trade or business of any kind is, to that extent, void. A confidentiality clause that protects genuine trade secrets is fine; a clause drafted so broadly that it stops a person from working in their field will be struck down as a disguised non-compete. In V.F.S. Global Services Ltd. v. Suprit Roy, the Bombay High Court held that a post-employment restriction preventing someone from joining a similar business for two years was not valid under Section 27. By contrast, restrictions that operate during the relationship are upheld, as the Supreme Court confirmed in Niranjan Shankar Golikari v. Century Spinning and Mfg. Co. The lesson for drafting is precise: a confidentiality obligation can survive after the contract ends, but a restraint on the person's trade generally cannot.
Three further points decide whether your NDA stands up in court. First, stamping. Under the Indian Stamp Act 1899 and the State stamp laws, an unstamped or insufficiently stamped agreement can be refused as evidence until the duty and penalty are paid, so the document must be stamped on the value and in the State where it is signed. Second, registration. Under the Registration Act 1908 you are not required to register an NDA, but doing so creates an official record that helps in a dispute. Third, electronic execution, which is recognised under the Information Technology Act 2000 for most commercial contracts. For the official text of the contract statute, see the India Code repository of the Indian Contract Act 1872 maintained by the Government of India.