Mr Ambani, who heads the telecoms-to-retail group Reliance Industries, says the high-speed network will be introduced first in major cities, including New Delhi and Mumbai.
He said it will then be expanded to the rest of India by December 2023.
The company is also working with Google to develop a budget 5G smartphone.
Speaking on Monday at Reliance's annual general meeting, Mr Ambani said that once the firm's 5G network is fully operational it would be the biggest in the world.
The service will be rolled out through Reliance's subsidiary Jio - which is India's largest mobile carrier.
Mr Ambani also said that Reliance was working with US technology giant Google to develop an "ultra-affordable" 5G smartphone, without giving further details on its price or planned launch date.
The cheapest 5G-ready smartphones in India currently cost around $150.
The announcements came as the battle for domination in India's digital future is heating up.
Earlier this month, the Indian government concluded a record $19bn auction for airwaves, including 5G airwaves, where Jio emerged as the top buyer.
It also drew bids from other major players Vodafone Idea and Bharti Airtel - and a fourth new entrant, Adani Data Networks.
The fifth generation of high-speed mobile internet - or 5G - supports emerging technologies such as driverless cars and artificial intelligence.
It seen to be central to India's plans to transform the country into a $1tn digital economy.
In May, Prime Minister Narendra Modi said that 5G would "not only accelerate internet speed but also boost development and employment."
During the wide-ranging address to investors, Mr Ambani also laid out a succession plan for his business empire.
The 65-year-old confirmed that his daughter Isha would head Reliance's retail ventures, while his youngest son Anant would join its new energy business.
His eldest son Akash was appointed as the chairman of Jio in June this year.
With an estimated net worth of $91.9bn, Mr Ambani is the eleventh richest person in the world and the second richest person in Asia, according to the Bloomberg Billionaires Index.
His late father Dhirubhai Ambani founded a textiles manufacturer that would eventually become Reliance Industries.
It is now India's largest conglomerate by market value, with businesses including petrochemicals, oil and gas, telecoms and retail.
How Ambani is teaming up with Zuckerberg
Mukesh Ambani's $25bn pledge to launch 5G services, is aimed to further edge out competition not just in telecoms but also retail.
The second part of that plan will see two giants joining forces - Mr Ambani's Reliance and US technology giant Meta - formerly known as Facebook.
In a country of 1.4 billion people, there are nearly 500 million users of Meta's WhatsApp platform - a user base Mr Ambani is hoping to entice with his online retail offering.
India is also WhatsApp's largest market and Meta boss Mark Zuckerberg, has been looking to push its WhatsApp business platform - which allows commerce on the messaging platform - for over a year now.
With this collaboration, Reliance will be able to extend its reach in the online retail sector. And for Meta, partnering with a leading player like Reliance and making its services available to all users on WhatsApp, gives it a stronger hold in India.
India is home to a nearly $700bn retail market and we have seen big businesses jostling to dominate that space.
Reliance Retail operates India's fastest growing and most profitable retail business, with over 12,000 stores across the country.
And with their combined might they hope to take on and beat online retail giants like Amazon and Walmart-owned Flipkart.
Italy's antitrust authorities penalized Amazon and Apple a total of more than EUR 225 million for suspected anti-competitive collaboration in the sale of Apple and Beats items. According to the competition watchdog, contractual clauses of a 2018 deal between the businesses permitted only chosen resellers to sell Apple and Beats items on Amazon, which was in breach of European Union laws.
The authorities fined Amazon EUR 68.7 million and Apple EUR 134.5 million, ordering the businesses to remove the limitations and provide sellers of authentic Apple and Beats items non-discriminatory access to Amazon. Apple has denied any wrongdoing and stated that it intends to appeal the sentence.
"We work closely with our reseller partners to guarantee our consumers purchase authentic items, and we have dedicated teams of specialists throughout the world who engage with law enforcement, customs, and merchants to ensure only genuine Apple products are sold," it stated. A...
WASHINGTON, April 21: More than a year into the Covid-19 pandemic, millions of American remain jobless, but even as the economy reopens some employers are finding hiring an unexpected challenge.
From fears of being infected with the coronavirus to trouble finding childcare to the lure of generous unemployment benefits, some jobless Americans are holding off on re-entering the workforce.
"It's a paradox for the Covid crisis," said Gregory Daco, chief US economist at Oxford Economics. "We have, and risk having over the coming months, an imbalance between job openings and demand."
The US economy has begun to recover as Covid-19 vaccines allow businesses to return to normal, and companies are starting to recruit to meet growing demand.
But not all unemployed workers are ready to return to their jobs, analysts say.
"The main issue is we still have a pandemic, and there is huge concern among job seekers about workplace health and safety," said Julia Pollak, an economist for job search website ZipRecruiter.
A quarter of the US population is fully vaccinated, well ahead of Europe and many other major economies, but three-quarters of the country nonetheless remains at risk of contracting Covid-19.
And childcare is another challenge for working parents, since only a little more than half of the nation's schools are back to full-time classes after the pandemic forced them to close or modify operations, according to FutureEd, a think tank at Georgetown University.
- Search for 'better conditions' -
The Covid-19 pandemic destroyed 22 million jobs in the world's largest economy, of which more than half, 14 million, have been restored.
However, nearly 17 million people are still receiving government unemployment aid, including self-employed workers, and many are working part-time because they cannot find full-time work.
But Daco said worker shortages are being seen across multiple sectors, including some of those hardest hit by the waves of layoffs, like retail, food service, hospitality and entertainment.
In a survey of US businesses conducted between late February and early April, the Federal Reserve noted "hiring remained a widespread challenge, particularly for low-wage or hourly workers, restraining job growth in some cases."
A hotelier surveyed by the Federal Reserve bank in Richmond, Virginia reported that "they were able to hire some front desk workers but had unfilled cleaning staff positions and little interest from workers in those jobs."
The central bank's Chicago branch reported a number of factors keeping unemployed workers at home, including "financial support from the government," like the extra $300 weekly benefit jobless employees will receive through August.
The Chicago Fed cited other complications in the hiring process including finding childcare, concerns about the virus, difficulty obtaining public transportation and "job search fatigue."
ZipRecruiter's Pollak said some workers also are fearful that if they take a job, they will simply be let go again.
"Many people experienced getting laid off as a really hard blow," she said, comparing the situation to people "who got divorced now being scared to go back into the dating market and get married again."
"They're not in a rush to put themselves back in a vulnerable position, especially since the extended and expanded benefits are giving them a little bit of time," Pollak said.
- Coaxing workers -
Some Americans have taken to working from home, which makes it easier to combine work with family life and not spend time commuting.
"Many people are not prepared to go back old jobs they had," Pollak said, and are instead holding out for remote work opportunities.
This trend has hit the restaurant industry in particular, which is hoping to see a rebound in the spring and summer after the pandemic forced many to close starting in March 2020.
"As the weather improves and more state restrictions are lifted, restaurant traffic will increase and that will create a greater need for employees," Hudson Riehle, who heads research for the National Restaurant Association, told AFP.
"With fewer people in the workforce, the stimulus supports still in place, worker safety concerns and much greater competition with other industries for workers," Riehle predicted some eateries may offer higher pay or additional benefits and opportunities to coax workers.
Amazon, Costco, Target and Walmart -- which run some of the largest distribution firms in the United States -- already announced pay increases.
