"India has won! Bharat ki Vijay. Ache din ane wale hai (good days are ahead)," Modi, who is all set to become prime minister, tweeted.
Modi later met his mother to seek her blessings.
In initial trends, BJP alone was leading in 275 seats - its best ever tally in Lok Sabha polls, while the NDA is set to cross the 300-mark. The earlier best by BJP was 182 seats in the 1999 Lok Sabha polls when the party formed its government led by Atal Behari Vajpayee.
Top BJP leaders including L K Advani and Rajnath Singh congratulated Modi for the party's electoral victory.
Buoyed by the party's stellar performance, celebrations started at the party's Delhi headquarters right from the time initial trends started trickling in and workers and leaders danced to the beats of 'dhols' and distributed sweets.
Modi, who is contesting from Vadodra and Varanasi was leading at both the places. While he was leading with a hefty margin of over 5.6 lakh votes in Vadodra, in Varanasi he was leading by over one lakh votes.