After inaugurating the Wall of Unity, Modi would offer floral tributes to Patel, whose birth anniversary falls on October 31.
The 182-metre imposing monument is twice the height of the Statue of Liberty in the U.S. and is built on an islet, Sadhu Bet, near the Sardar Sarovar Dam in Gujarat's Narmada district.
The 42-month project built by 250 engineers and 3,000 workers began in 2013, when Modi was the top elected official in Gujarat.
The Prime Minister will reach Ahmedabad today evening and stay overnight at Raj Bhavan.
Questioning the critics of the structure, Modi said it "amazed" him that "some people" would "see this initiative from a political view" and "criticise us like we committed a huge crime". Is remembering country's great personalities a crime?: PM Modi.
Chotu Vasava, a local legislator and community group leader, repeated a threat to stage protests on the eve of the ceremonies around the statue of Patel, who played a key role in unifying India after its independence in 1947. He has converted India's diversity into its biggest strength.
"Two traits synonymous with Sardar Patel are trust and integrity".
Governor of Gujarat OP Kohli, Chief Minister Vijay Rupani and BJP chief Amit Shah were present at the unveiling of the Statue of Unity.More news: Tremors felt in Malta after natural disaster in Greece
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It has became an example of Modi's Bharatiya Janata Party's (BJP) efforts to appropriate a popular national figure, as Patel was a member of the Congress Party, which now sits in opposition to BJP in India's parliament.
An astonishing £330 million (Sh431 billion) has been spent on the 600ft tribute to Indian independence leader Sardar Vallabhbhai Patel in his home state of Gujarat.
A campaign called "Loha" was launched to collect iron from all over the country to build the statue of Sardar Patel.
"Instead of spending money on a giant statue, the government should have used it for farmers in the district", Vijendra Tadvi, a farmer who also worked as a driver on the statue's construction site, told BBC Gujarati's Roxy Gagdekar.
The statue, whose foundation was laid by Modi in 2013 as chief minister of Gujarat, will dwarf the current tallest statue, the Spring Temple Buddha in China (128m), and will be nearly double the height of the Statue of Liberty in NY.
The height of Statue of Liberty is 93 metres, including its pedestal.
The Gujarat government is reported to have paid more than half of the funds for the statue, while the remainder came from the federal government or public donations.