At 597 feet, the statue, built at a cost of $430 million, is the tallest in the world, nearly twice as tall as the Statue of Liberty, the BBC reports.
The statue is part of a broader project by Modi to counter the opposition Indian National Congress Party's firm claim on India's history by way of the country's first prime minister, Jawaharlal Nehru, his mentor, peace activist Mahatma Gandhi, and his daughter, former Prime Minister Indira Gandhi, who was assassinated by her guards in 1984.
Three Indian Air Force planes flew past the Patel figure and created the tricolour in the sky after Modi inaugurated the giant. Our constitutional rights are not upheld.
The Congress, which otherwise leaves no stone unturned to criticise every move of the PM Modi-led BJP government, seemed rather subdued over the unveiling of Statue of Unity.
Including the pedestal, the Statue of Liberty stands about half as tall at 305 feet.
Gandhi said Patel was a patriot, who fought for a independent, united and secular India.
"The "Statue of Unity" [of Patel] is a symbol of both the unity of hearts and the geographical integrity of our motherland".
Prime Minister Narendra Modi on Wednesday unveiled the world's tallest statue - Statue of Unity - at Kevadiya Colony in Narmada district on the birth anniversary of India's Iron Man Sardar Vallabhbhai Patel on Wednesday.
The Modi administration hopes to turn the statue into a tourism hub and is developing infrastructure such as motorways and hotels around the structure.
It is almost twice as tall as New York's Statue of Liberty.
Sardar Patel is credited for unifying all of the 562 princely states in pre-independence India to form what is today the Republic of India. "It will be a place to visit for those nostalgic about the freedom struggle". Hundreds of Chinese have been among the 3,500 workers involved in its construction.
Jiangxi Tongqing Metal Handicrafts, a foundry in southeastern China, was tasked with the bronze panelling of Patel's statue. The BBC reported that locals have expressed deep concern that they still lack basic irrigation facilities vital to the region's economy while mass investment has been diverted to a largely-ceremonial project. The government in the western state of Maharashtra is constructing a memorial to the Maratha warrior king Shivaji that is estimated to be 190m tall. The current design would make it 212m high.