Some of the celebrations will be held in the Ambani’s 27-storey skyscraper, complete with a swimming pool, ballroom and cinema, that towers over the city.
On Friday, Rolls-Royces covered in beaded nets began to trundle into the main wedding site, disgorging VIPs behind layers of security.
The happy couple kicked off celebrations two-weeks ago with a four-day cruise through Europe, along with private performances from Justin Bieber, Rihanna and the Backstreet Boys.
About 100 private planes were reported to be transporting the guests to the wedding.
The total cost has been estimated at £462 million.
Those who did not make the cut offer criticism rather than congratulations.
The gulf between India’s rich and its poor has widened to a record level for the last 60 years, according to research by the World Inequality Lab.
Locals were furious when the government labelled the wedding a “public” event when the public will be held at arm’s length.
It has also upgraded the status of the local airport from domestic to international and pressed a wide variety of public servants and military figures into service for the Ambanis.
“It’s such a shame that people are made to suffer for a private family wedding in a country where young men like me are jobless,” Mahinder Vishvakarma, a 30-year-old software engineer at Nucsoft Pvt Ltd told the Telegraph.
“The family could have opened a few schools in each Indian state,” added Usha Pandit, a teacher. Instead we have this tasteless jamboree of the Ambanis grinning around like a bunch of jackrabbits.
“I dread to think of the food wasted, the costs of lighting, transport, security, traffic snarls, and inflation in hotels. Down the drain, adding nothing to the family but contempt.”
SW Nimkar, 60, said: “Ambani is paying huge taxes to the government and has every right to hold such a lavish wedding. The Government is failing us, not Ambani.”
Hotels ramp up prices
Tourists unaware of the festivities may also have reason to resent the festivities. One hotel was charging £6,000 for a room over the weekend, up from a typical rate of £130.
Mr Modi’s decision to attend marks a reversal from when he was accusing the Ambani family of paying bribes to his political rivals earlier this year.
With polls showing a tighter contest than many expected, the Hindu nationalist leader tried to seize upon growing public distaste for the antics of India’s ultra-wealthy. It was a breach from years of chummy relations.
In January, Mr Ambani Snr who is the chairman of Reliance Industries, which has interests in energy and petrochemicals, praised Mr Modi for his “vision and consistency” and called him “the greatest global leader of our times”.
In March, his son and husband-to-be paid tribute to Mr Modi’s campaign to promote weddings in India.
“It’s a matter of pride and happiness when our PM said that one should get married in India,“ he said.
During the recent election campaign, Rahul Gandhi, the leader of the opposition Congress Party, accused Mr Modi of illegally taking money from Mr Ambani Snr.
Mr Modi denied the accusations and responded in kind, suggesting Mr Gandhi had stopped criticising Mr Ambani because he had been bought off with “truckloads of some illegal funds”.
Mr Gandhi replied: ”Is it your personal experience that you know they give money in trucks?“
”I want to repeat to the nation that the amount of money Modi has given to them, we are going to give the same amount to India’s poor.“