Although Delhi accounts for only 70 of the 4,120 assembly seats in the country, the AAP's spectacular showing had its predictable fallout, with opposition parties and even BJP ally Shiv Sena taking potshots at Modi.
The win gave the AAP, India's youngest political outfit, 96 percent of seats in a legislature - another record - and a new lease of life after it was written off following its earlier turbulent 49-day stint in Delhi and the later humiliating rout in the 2014 Lok Sabha battle.
So stunning and sweeping was Tuesday's victory in what was supposed to be a tough election with Prime Minister Narendra Modi himself leading the BJP's charge that many AAP leaders and workers who had slogged for months broke into tears.
Kejriwal, 46, had teary eyes as AAP colleagues repeatedly hugged him and lifted him in the air, and congratulatory messages poured in from all over the country thick and fast. Outside his home, thousands kept chanting the party's catchy line: "Paanch Saal, Kejriwal!"
The Congress simply sank, with its chief campaigner Ajay Maken resigning as the party's general secretary after he finished third in his Sadar Bazar constituency. Most Congress candidates lost by huge margins, one by 95,000 votes.
The BJP suffered far more humiliation, with its chief ministerial candidate Kiran Bedi, who had been personally picked by Modi, losing to a little known advocate of the AAP. Two of the three BJP winners scraped through by just 5-6,000 votes in contrast to the giant margins scored by AAP candidates.
With the BJP subdued, Modi, who led an aggressive campaign against Kejriwal and called him a "Naxalite" (Maoist) who should be banished to the forests, congratulated the AAP leader and offered his government's full cooperation.
The AAP said Kejriwal will take oath as Delhi's chief minister Saturday, exactly a year after he resigned. Delhi Police said it will provide "Z" category security that would include at least 30 commandoes to Kejriwal.
Kejriwal later reached the AAP office in central Delhi where he told boisterous supporters waving party flags and brooms -- the AAP election symbol -- that the AAP sweep was "a victory for truth and honesty".
He also urged his supporters not to become arrogant, pointing out that it was arrogance which had first decimated the Congress in Delhi and now the BJP. "This is incredible. We can't believe it," AAP leader and former Delhi minister Manish Sisodia told IANS. Senior AAP leader Yogendra Yadav called it a victory of proverbial David over Goliath.
In remarks directed at Modi, West Bengal Chief Minister Mamata Banerjee, who had asked people in Delhi to vote for the AAP, said it was a "big defeat for the arrogant and those spreading hate". "The election is a turning point... The country needed this change."
Gandhian Anna Hazare added: "The result is a defeat for Narendra Modi. What did the BJP do in the past nine months? The BJP made promises to tackle corruption. Instead they took anti-people, anti-farmer decisions."
Former Jammu and Kashmir chief minister Mufti Muhammad Sayeed said: "The Delhi elections have asserted the diversity of our country and the need to respect it which the BJP should learn not to ignore." In Mumbai, Shiv Sena president Uddhav Thackeray termed the AAP sweep a 'tsunami'. "This is a great day for democracy. It was not just a wave. It was a tsunami which swept Delhi. I agree with Anna Hazare that this is a defeat for Modi, not (Kiran) Bedi." The AAP was, however, more circumspect in its assessment. "It is a giant leap for a small party," AAP ideologue Yogendra Yadav told the media. "We still have a long way to go (vis-a-vis national politics). We have just got a toe-hold."
One after another, BJP leaders accepted defeat and congratulated the AAP and Kejriwal. Said Satish Upadhyay, the party's Delhi unit head: "Clearly, we made a mistake in understanding the people's mood." "We accept our massive defeat," added Communication Minister Ravi Shankar Prasad. Bedi, whose induction as the BJP's chief ministerial candidate caused fissures in the party, said: "I have not lost. Let the BJP assess why they lost. I gave my very best."
The AAP is set to bag an incredible 54 percent of all votes. It swept all parts of the capital, including the middle class areas as well as the numerous low income neighbourhoods. All social classes, including Muslims and Christians, voted for it overwhelmingly.
Kejriwal himself won easily from New Delhi constituency, where he created history in 2013 by defeating three-time chief minister Sheila Dikshit. Most AAP leaders also made it comfortably, including Somnath Bharti, Manish Sisodia and Rakhi Birla, who were ministers in the earlier Kejriwal government.