The invites customers in these four cities will get unlimited 5G data with up to 1 Gbps+ speeds.
The Beta trial service for other cities will be announced progressively as cities keep getting ready, said the company.
The users will continue to avail of Beta trial "until the network coverage of a city is substantially complete to provide the best coverage and user experience to every customer," it said.
The company said that invited 'Jio Welcome Offer' users will be automatically upgraded to the Jio True 5G service without needing to change their existing Jio SIM or 5G handset.
Akash M. Ambani, Chairman, Reliance Jio Infocomm Ltd, said that Prime Minister has given a clarion call for accelerated roll-out of 5G across India to realise the full potential of a Digital India.
"In response, Jio has prepared an ambitious and the fastest ever 5G roll-out plan for a country of our size," said Ambani.
Jio said it is also working with all handset brands to enable their 5G handsets to work seamlessly with Jio True 5G services so that customers have the most comprehensive range of 5G devices to choose from.