Indian media reports said Modi was likely to be sworn in as prime minister on Sunday.
Regional leaders including Sheikh Hasina of Bangladesh and Sri Lankan President Ranil Wickremesinghe have said they will attend the ceremony.
Modi insisted on Tuesday that the election results were a victory that ensured he would continue his agenda.
“Our third term will be one of big decisions and the country will write a new chapter of development,” Modi told a crowd of cheering supporters in the capital New Delhi after his win.
Commentators and exit polls had projected an overwhelming victory for Modi, who critics have accused of leading the jailing of opposition figures and trampling on the rights of India’s 200-million-plus Muslim community.
But the BJP secured 240 seats in parliament, well down from the 303 it won five years ago and 32 short of a majority on its own.
