Mr Shah chaired a strategic meeting of the six-party North- East Democratic Alliance (NEDA), which was attended by the chief ministers of five states -- Assam, Manipur, Sikkim, Arunachal Pradesh and Nagaland -- from the region.
"The BJP-led NEDA is in power in five states but I am confident that in the coming days, the alliance will be in power in all the eight states in the north-eastern region," he said at the inaugural session of the NEDA conclave in Delhi.
At present, the BJP is in power in Assam, Manipur and Arunachal Pradesh, while its allies rule Nagaland and Sikkim.
Assembly elections are due in three non-NEDA states -- Tripura, Meghalaya and Mizoram. Elections in Tripura, where the Left is in power, will be held later this year. Congress- ruled Mizoram and Meghalaya will go to polls early next year.
He said the region was top priority for Prime Minister Modi. Development in the eight states was essential for the overall growth of the country, he added.
"The development work done by the Modi government in the last three years for the long-neglected north-eastern region is several times more than the work done by Congress-led governments in the last 65 years," Mr Shah said.
The work had not finished but just started, he added. Citing numerous initiatives of the Modi government for the region, Mr Shah said a Union minister visited one of the eight states in the region every 15 days.
He termed the land boundary agreement with Bangladesh a milestone in the history of the north-east and said the government was committed to the overall development of the area.
Emphasising the importance of NEDA, he said, "It is not only a political platform but a platform to culturally unite all eight north-eastern states and increase their involvement in national affairs".
Talking to reporters, NEDA convener Himanta Biswa Sarma later said it was confident of seeing a "Congress mukt" (Congress-free) north-east by November 2018.
Mr Sarma, a minister in the BJP government in Assam, has been a key figure in expanding the party's footprints in the region.
Safe borders, inclusive development and national integration were on the agenda of the day-long NEDA meeting.
North-east states have used the NEDA platform to sort out boundary, law and and other disputes, Mr Sarma said at the meeting.
The BJP-led NEDA consists of the Naga People's Front, Sikkim Democratic Front, People's Party of Arunachal, Asom Gana Parishad and Bodoland People's Front.