The Bharatiya Janata Party (BJP) has not lost in the western industrial state since 1995 and Modi served as its chief minister for nearly 13 years before becoming the prime minister in 2014.
Opinion polls conducted in the lead-up to the Gujarat polls projected the BJP to comfortably retain power in the state despite criticism of inflation and unemployment.
The Aam Aadmi Party (AAP), which was formed only a decade ago and has claimed power in Delhi and the state of Punjab, is set to become one of the main opposition parties in the state of more than 60 million people, at the expense of the Congress party.
The second phase of voting is on Monday and results are due on December 8.
In the last state election five years ago, the BJP won 99 seats in the 182-member assembly while Congress took 77.
According to an India TV-Matrize opinion poll, also conducted in November, the BJP may win up to 119 seats.
The AAP has promised voters subsidies on electricity and other bills in their bid to become the main challenger to the BJP.
Congress, on the other hand, launched a cross-country “unity march” in September against what it calls “hate and division”, hoping to revive its fortunes and regain some popularity.
The right-wing party also expects to emerge victorious in assembly elections in Himachal Pradesh state in the north, which were held last month with results to be declared on December 8.