The final round of counting votes concluded in Tripura with the BJP winning 32 seats.
The Tipra Motha Party (TMP) won 13 seats in its electoral debut.
The Communist Party of India (Marxist), which ruled the state for more than three decades until 2018, won 11 seats.
The Congress secured three seats followed by BJP's ally Indigenous People's Front of Tripura (IPFT) winning one seat.
Defence Minister Rajnath Singh and Home Minister Amit Shah congratulated Nagaland's incumbent CM Neiphiu Rio and the state BJP team for their resounding poll victory.
Meghalaya's incumbent Deputy CM Prestone Tynsong won the Pynursla seat by a margin of 8,140 votes.
After his victory was announced, Tynsong said, "In Meghalaya's politics, individual candidates matter more than the party. It is the nominees who win the elections, not the party."
After a convincing victory, PM Narendra Modi took to Twitter to thank the people of Nagaland.
He lauded his party workers for their effort and hailed the "double engine" government saying that it will keep working for the state's progress.
The ruling NPP emerged victorious in 19 seats and is still leading in six seats.
The UDP became the state's second-largest party by winning 11 seats.
The Congress and TMC won five seats each.
The Voice of the People Party (VPP) secured four seats while the BJP won seats and is leading on one, as per the Election Commission (ECI).
After an impressive performance in its debut electoral contest, the Tipra Motha Party (TMP) led by Pradyot Manikya Deb Burman celebrated his tribal-dominated party winning 13 seats.
Deb Burman said that his party's growing influence will ensure that the BJP can't sideline the tribal issues.
Amid the counting of votes of the Assembly elections, Union Civil Aviation Minister and BJP leader, Jyotiraditya Scindia said that the blessings of the people are with the BJP's Trimurti, referring to PM Narendra Modi, Home Minister Amit Shah, and BJP president JP Nadda.
With the NDPP winning 23 seats and leading on two, combined with the BJP's victory on 12 seats, the incumbent alliance is likely to remain in power.
TMC's Mizanur Rahman Kazi defeated NPP's Abdus Saleh with a slim margin of 10 votes to win the Rajabala constituency.
The incumbent NPP has won four seats in Meghalaya, namely Raliang, Rangsakona, Jowai, and Nartiang.
Although CM Conrad Sangma is leading on the South Tura seat, his brother James Pangsang K Sangma was defeated by TMC's Rupa Marak in the Dadenggre constituency by a margin of merely seven votes.
NDPP's Hekhani Jakhalu won the Dimapur-III seat by a margin of 1,536 votes to become the first woman MLA to be elected in Nagaland.
Union Law Minister and BJP leader from Arunachal Pradesh, Kiren Rijiju on Thursday said, "If we're winning elections, it means we're winning people's confidence. There will be only BJP's impact in all states in the northeast."
Inching closer to the magic number of 31 in Tripura, the incumbent BJP said that it was ready to accept all demands of the Tipra Motha Party (TMP), except Greater Tipraland, a separate state for the indigenous.
The BJP has won four seats and is leading on 29 out of the total 60 seats while the TMP has won a seat and is leading in 12 constituencies.
After trailing in the earlier rounds of counting, Nagaland BJP chief Temjen Imna Along made significant gains to edge ahead of Janata Dal (United) candidate J Lanu Longchar by 1,202 votes in the Alongtaki Assembly constituency.
Meghalaya's ruling party NPP has won two seats and is leading in 21 constituencies. Its alliance partner, the BJP is ahead on three seats.
The TMC is leading on five seats and the UDP on 10 seats while the Congress has a winning edge in four seats.
Communist Party of India (Marxist) candidate Nayan Sarkar defeated BJP's sitting MLA Krishnadhan Das by a margin of 1,854 votes in the Bamutia Assembly constituency of northern Agartala, Tripura.
Tripura's incumbent Education Minister and BJP leader, Ratan Lal Nath defeated TMP's Tapas Dey by 7,347 votes to clinch the Mohanpur Assembly seat. Congress nominee Prasanta Sen Chowdhury trailed Dey by 1,480 votes after the final round of counting.
Republican Party of India (Athawale) candidate Imtichoba defeated NDPP's K Odibendang Chang by a margin of 500 votes in Nagaland's Tuensang Sadar-II seat.
With a margin of 44 votes, Meghalaya's incumbent CM Conrad Sangma is having a tough battle against BJP's Bernard Marak in the South Tura constituency.
Tripura's incumbent CM, BJP's Manik Saha won the Town Bordowali seat by defeating Ashis Kumar Saha of the Congress.