With military aircraft scattering flower petals on the statue from the skies, Mr Modi paid tribute to Patel and the occasion, in what was effectively the unofficial launch of his campaign for re-election next year.
Earlier in the day, Modi said that he bow to the great Sardar Patel, the stalwart who unified India and served the nation tirelessly, on his Jayanti.
Mayawati said that Sardar Patel had a following all over the country and was respected by people cutting across caste and community, but dragging him into regional politics shows the "narrow-mindedness" of BJP leaders. Modi also reiterated Sardar's vision that every Indian will have to forget about one's caste and class and identify oneself as Indian.
The Statue Of Unity is the world's tallest statue standing at 182 metres.
The statue is part of Modi's poll promise which helped the BJP come to power in 2014 by defeating the Congress.
India on Wednesday inaugurated the world's tallest statue, a $400-million effigy of independence hero Vallabhbhai Patel that towers almost twice the height of New York's Statue of Liberty.
Stray fingerprint and bad spelling pointed to bomb suspect
Lowy, who represented Sayoc, said he showed no ability at the time to back up his threat with bomb-making expertise. The FBI says DNA evidence and a fingerprint on the pipe bomb packages led them to Sayoc in Aventura, Florida .
The accusations are a distortion of history, says Congress, which ruled India for much of its independence history and is now led by Rahul Gandhi, the great-grandson of Jawaharlal Nehru, India's first prime minister. The unveiling of the statue comes ahead of the Lok Sabha polls next year.
Online booking to visit the Statue of Unity has opened with a 350 rupee ($4.75) admission fee for the 153-meter-high observation deck.
Modi was accompanied by Chief Minister Vijay Rupani. "It is a tribute to the man who united India, Sardar Patel".
It is situated in Gujarat, about 100 km's (60 miles) from the nearest city of Vadodora.
The project also includes a memorial park at the base of the statue, a visitor facilitation centre and a reception desk.
Thousands of policemen guarded the venue during the inauguration, as local tribal people have been holding protests in recent months claiming the project had destroyed natural resources, the Times of India newspaper reported.
She said like Dalit leader Baba Saheb Ambedkar, Sardar Patel was also a nationalist and was widely respected.