Facebook, which has about 400 million users in India, said it wanted to connect the "power of WhatsApp", its messaging subsidiary, with the Indian platform, which has grown on the back of a massively successful telecom venture.
In four years Ambani has turned his Jio telecoms unit into the country's biggest mobile operator - with 388 million subscribers - clobbering competitors with aggressively low pricing.
Jio Platforms also provides internet and e-commerce services that tap into the huge subscriber base.
Reliance said it wanted to boost income for farmers, micro-traders and other small businesses that are the cornerstone of the economy in the country of 1.3 billion.
The company is expected to roll out an e-commerce initiative this year and has been conducting trials with small stores to test its payment devices.
"Jio digital new commerce platform and WhatsApp will empower nearly 30 million small Indian Kirana (grocery) shops to digitally transact with every customer in their neighbourhood," Ambani said in a video statement.