Cash-rich Reliance, controlled by India's richest man, Mukesh Ambani, has been diversifying into businesses including retail, financial services and telecommunications to counter slowing growth in its core oil and gas business.
Reliance, India's second-largest company by market value, had first invested an undisclosed amount in Network18 and its subsidiary TV18 Broadcast in 2012, marking its entry to the media sector.
The conglomerate returned to the telecoms sector in 2010 by winning a nationwide permit for 4G broadband services, but has yet to start commercial services.
"The broadband business, if developed right, has a very high potential of success and Reliance understands that," said Deven Choksey, chief executive of brokerage KR Choksey Shares & Securities in Mumbai.
"The media properties of Network18 are a natural fit and have the potential to make them a differentiated content provider."
Network18, founded by entrepreneur Raghav Bahl, runs business news portal moneycontrol.com and a few other news and e-commerce websites, while TV18 operates television channels including CNBC-TV18 and CNN-IBN.
Independent Media Trust (IMT), set up by Reliance, will use the funds to acquire ownership of about 78 percent in Network18 and 9 percent in TV18, the company said.
IMT will also make a mandatory tender offer to minority shareholders for acquisition of more shares in Network18, TV18 and group company Infomedia Press Ltd, the Reliance statement said.
The Reliance entity will make the tender offer to buy the remaining 21.96 percent in Network18 for 9.4 billion rupees ($159.28 million), while it will offer to buy up to 26 percent each in TV18 and Infomedia for a combined 17.4 billion rupees.
Network18 posted a 195.7 million rupee ($3.3 million) loss for the quarter ended March 31, which had widened from a loss of 159.6 million rupees in the same period a year earlier.
Reliance held cash reserves of $14.4 billion at the end of December and was debt-free on a net basis.
($1 = 58.8750 rupees)