Anant Ambani is expected to tie the knot with Radhika Merchant, daughter of Indian pharma tycoons Viren and Shaila Merchant, in a traditional Hindu ceremony in Mumbai city on Friday.
The wedding events began with parties and celebrations in March.
The months-long festivities have been attended by top Bollywood stars, musicians and business tycoons like Bill Gates and Mark Zuckerberg.
On Friday, reality TV star Kim Kardashian, former UK PM Tony Blair and Nigerian rapper Rema were among those who landed in India's financial capital to attend the festivities.
The couple's wedding celebrations are likely to continue over several days. Parties have been reportedly planned for Saturday and Sunday and a grand reception is scheduled for Monday.