The red carpet was set up in a room adorned with lanterns and red and orange garlands and floral arrangements. Mr. Zala, a photographer working for Manav Manglani, one of Bollywood’s top paparazzi, had already shot several of the couple’s prewedding functions, which began in March.

It’s not every day that Kim and Khloé Kardashian, John Cena and Boris Johnson gather in Mumbai for an Indian wedding. All four were in attendance on Friday at the Jio World Centre in traditional Indian garb.

Mr. Zala was one of about 100 media members clamoring next to the red carpet, not a common addition at most weddings. But given the sheer number of celebrities present — Bollywood superstars, several members of the Indian cricket team, former prime ministers and billionaire businessmen — and the fabulous Indian clothes on display, a runway seemed in order.

When Mr. Cena came out wearing a baby-blue sherwani, one photographer shouted, “Welcome to India.”

As Khunying Patama Leeswadtrakul, a Thai businesswoman, and her husband, Somsak, posed for photographers, a young stylist interrupted to adjust Ms. Leeswadtrakul’s scarf. The stylist, who seemed to have been hired just to help guests be camera-ready, stood at the side of the room for the duration of the eight-hour red carpet arrivals.

It was then that the Ambani family made its way onto the red carpet: the groom, Anant Ambani; his mother, Nita Ambani; his father, Mukesh Ambani; and his brother and sister and their spouses and children.

Inside the wedding, the reggaeton singer Luis Fonsi performed his hit song “Despacito.” The Afrobeats star Rema and the Bhangra singer Sukhbir also performed. The Indian actor Ranveer Singh danced energetically to a song whose music video he himself starred in, “Tattad Tattad,” in the event hall, which was showered with confetti. The Bollywood actress Ananya Panday and the Indian cricketer Hardik Pandya grooved to “Zoobi Doobi,” and the Bollywood superstars Shah Rukh Khan and Salman Khan danced together as well.

Friday’s ceremony was followed by a reception on Saturday, and India’s Prime Minister Narendra Modi attended. Former British Prime Minister Tony Blair was seen shaking hands with the president of FIFA, Gianni Infantino.

For the Saturday reception, Ms. Merchant wore a pink lehenga crafted by Abu Jani Sandeep Khosla in collaboration with the Indian artist Jayasri Burman, who hand-painted the cloth with animals, including elephants, and depictions of the couple.

On Sunday, the mangal utsav was held, a reception that was the largest event of the wedding weekend. Ms. Merchant wore a gold corset from Dolce & Gabbana paired with a satin sari by Anamika Khanna. A. R. Rahman, and Shreya Ghoshal, two of India’s most prolific singers, performed classic Indian songs including “Tere Bina” and “Barso Re.”

On Monday night, there was a final reception for employees of Reliance Industries.

Many onlookers had opinions about the nuptials: It’s fun and exciting; it’s too long; it’s bringing international attention to Indian festivities; it exposes significant wealth disparities in the country.

“They’ve taken the big fat Indian wedding term very seriously, and they’re sort of showing you the most grand scale,” said Anjan Sachar, a journalist from Mumbai, in a cafe in Bandra, the same neighborhood where the wedding festivities took place. “Weddings are always a big deal in India. No matter what caste, what state, doesn’t matter. And with the Ambanis, they’re one of the richest families in the world. It’s also their last child’s wedding.”

But some guests, who did not want to be identified discussing the Ambani family’s personal affairs, said that the wedding was overcrowded and hectic, and that they felt a level of fatigue regarding the never-ending festivities.

Since March, the lead-up to the celebration has been a carefully orchestrated spectacle, capturing the attention of an international audience.

On the morning of the ceremony, decorations covered the surrounding streets of the Jio World Centre, an 18.5-acre business and cultural center owned by the Ambanis. Hundreds of people working for the wedding stood outside waiting to receive badges that would grant them access on-site: photographers, musicians, cooks, event staff, carpenters, dancers and makeup artists. Several roads were closed off in the busy area, leading many residents to complain about the traffic.

While the Ambanis’ enormous wealth and clout are well known in India, many people outside the country might not have even heard of them before Rihanna performed at the couple’s three-day prewedding bash in Jamnagar, a town in the western Indian state of Gujarat. Mark Zuckerberg and Bill Gates were also in attendance.

In June, the festivities continued on a cruise ship in Europe with performances by Katy Perry, the Backstreet Boys and Pitbull. And on July 5, the extravaganza kicked off in Mumbai, with a performance by Justin Bieber at the sangeet, traditionally a night of music and dancing leading up to the nuptials. (Himanshu Patel, who photographed the couple’s wedding and pre-wedding events with a team of 10 under his company Epic Stories, said he spent over 20 days shooting the monthslong festivities.)

Ms. Khanna, who designed several of the outfits for the wedding festivities, is a fixture in Indian fashion, but working on this wedding, she said, stood out for its “epic” level of visibility and attention. She said Ms. Merchant’s wedding weekend finale look was a “blend of Indian culture in modernity with something completely international.”

The majority of the looks for the wedding weekend came from India’s top designers, though Mr. Ambani and Ms. Merchant worked with houses like Versace and Robert Wun for the pre-wedding looks.

Abu Jani and Sandeep Khosla of Abu Jani Sandeep Khosla began designing the outfits over 18 months ago, and they worked to sustain traditional Indian craft and techniques through the looks. “This wedding couture had to pay homage to craft, textiles, family, nature, love and tradition,” Mr. Jani said.