The results are a ringing endorsement of Modi's popularity, his government's achievements in the last five years and his campaign, which centred around national security, nationalism and Hindutva.
The BJP got an absolute majority bagging 286 of the 458 seats, results of which were declared past midnight and was on course to cross the 300-seat mark in the 543-member Lok Sabha, leading in another 17 seats.
It surpassed its 2014 performance when it won 282 seats.
With the elections establishing the 68-year-old Modi as the most popular leader in decades, the BJP and its allies in the National Democratic Alliance are poised to clinch over 350 seats as against their previous 336.
Such was the force of the BJP wave that even Congress president Rahul Gandhi lost in his bastion of Amethi in Uttar Pradesh to Smriti Irani, but in consolation prize won the Wayanad seat in Kerala.
Former prime minister and Janata Dal-Secualr supremo H D Deve Gowda also bit the dust when he lost the Tumkur seat in Karnataka where the BJP bagged 25 of the 28 seats.
After Jawaharlal Nehru and Indira Gandhi, Modi is the third prime minister of the country and the first non-Congress one -- who has been able to retain power for a second term with full majority in Lok Sabha.
The victory margin left the combined opposition in the dust, with the Congress party topping the group winning or leading in 52 seats, according to the partial results.
Much like the 16th Lok Sabha in 2014, the lower house of the Parliament may be again bereft of the Leader of Opposition since going by the available trends, the Congress will fall short of the 54-mark needed for the LoP status but marginally improve its all time low tally of 44 in 2014.
The euphoria of the victory was capped by a sombre speech by Modi in which he promised to devote ‘every moment of my life and every fibre of my body’ to the welfare of the nation. He also vowed that he will never do anything with ill-intention, nor will he do anything to enrich himself.
“Whenever you judge me, judge me on these three parameters. If I fall short on these, curse me. But I assure my countrymen that what I have said in public I will do my best to fulfil," he said.
"We had gone to people seeking mandate to build a new India. People have given us their blessings for it."
Striking a conciliatory political tone, he also reached out to his rivals, urging everyone to put the rancour of the bitter and often nasty campaign behind them. What's past is past, he said.
“We have to move ahead. We have to take everyone with us, even our opponents. We have to work for the benefit of the country," he said.
"You have filled this fakir's bag with a lot of hope. All your hopes, dreams, ambitions are dependent on it," he told cheering partymen at BJP headquarters in the national capital.
Modi easily won his seat in Varanasi with a margin of over 4.5 lakh votes while party president Amit Shah took Gandhinagar in their home state of Gujarat by over 5.5 lakh votes.
‘With all+ development for all+ everybody's confidence = victorious India,’ Modi tweeted in his first reaction to BJP's landslide win.
"Together we grow. Together we prosper. Together we will build a strong and inclusive India. India wins yet again," he said.
Modi and Shah arrived at the party headquarters to a rapturous welcome by supporters. Modi waved victory signs with both arms in the air as rose petals were showered on the duo, the two most powerful men in the country.
He then proceeded to garland the statues of BJP idealogue Deen Dayal Upadhyaya and Shyama Prasad Mukherjee. Minutes later, a gigantic garland in BJP colours of saffron and green was held around Modi by other dignitaries.
In the end, Modi's proclamation of ‘Ab ki baar 300 paar’ just a few days ago looks set to come true as Gandhi's campaign slogan of ‘chowkidar chor hai’ and promises of annual income guarantee were soundly rejected by voters.
In almost all the states where BJP won, its vote share was more than 50 per cent while the Congress failed to open the account in 15 states.
The results have raised questions about Gandhi's leadership and his party's future. At a press conference, Gandhi refused to address that issue, saying the party will hold a meeting on Friday to discuss the future.
"The people of India have decided that Narendra Modi will be the PM again and I fully respect it," Gandhi said. He also congratulated Modi and BJP, adding that today is not the day to into the cause of the defeat but to respect the will of the people.
The results are a ringing endorsement of Modi's popularity, his government's achievements in the last five years and his campaign, which centred around national security following the Balakot air strikes, nationalism and Hindutva. He also relentlessly attacked the Congress Party for what he called its dynastic legacy, and blamed it for the country's woes, including endemic corruption.
The opposition had criticised the BJP campaign as divisive and polarising.
Still, the results show that the Modi wave and the party's brilliant election management swept across geographies, caste lines, age, gender and economic status.
"The politics of casteism, dynasty and appeasement politics has been buried in this massive mandate to BJP," Shah said in the presence of Modi.
In the politically critical state of Uttar Pradesh, where the Samajwadi Party-Bahujan Samaj Party combine had posed a stiff challenge, the BJP is expected to win 62 of the 80 seats at stake.
Although the BJP had won 71 seats in the last elections, the performance is far better than the 30-40 seats many exit polls had forecast.
The Modi wave not only swept through the Hindi heartland and Gujarat, as was expected, but also bulldozed through West Bengal, Odisha, Maharashtra and Karnataka. Only Kerala, Tamil Nadu and Andhra Pradesh appeared untouched.
Even in Telangana, where it was expected to fare poorly, the BJP won four seats, while the Telangana Rashtra Samiti got nine.
However, Andhra Pradesh threw up a shock in the assembly polls, which were held simultaneously, voting out of power the Telugu Desam Party of Chandrababu Naidu, and electing Jagan Mohan Reddy's Yuvajana Shramika Rythu Congress.
The results were staggering for BJP in the Hindi-speaking states, including those where Congress had won in the recent assembly elections: it swept all but one of the 29 seats in Madhya Pradesh, 24 out of 25 in Rajasthan and nine out of 11 in Chattisgarh.
Similar was the story in Bihar, Haryana, Himachal Pradesh, Uttarakhand, Maharashtra and Delhi.
Among the big-name casualties were Congress leaders Mallikarjun Kharge who lost his Kalburgi seat in Karnataka and Jyotiraditya Scindia in Guna Madhya Pradesh. Senior Congress leader Digvijay Singh lost the Bhopal seat to Sadhvi Pragya Sharma.
The BJP also made huge gains in Odisha, West Bengal and Telangana.
In Odisha, the BJP was ahead in eight of the 21 seats, up from one last time.
In West Bengal, it won 18 seats, up from two in 2014, all at the expense of the Left while the Mamata Banerjee-led Trinamool Congress’s tally came down to 22 from 34.
In Telangana, the BJP won four.
Congress ally Dravida Munnetra Kazhagam won 22 seats and was ahead in one of the 38 seats in Tamil Nadu while in Kerala, the Congress-led United Democratic Front won 18 out of 20 seats.