Cebu still holds the biggest voting population among the provinces at 2.5 million, records of the Commission on Elections (Comelec) said.
Comelec Regional Director 7 Temie Lambino said the registered voters in Cebu reached 2,509,520, including the highly-urbanized cities of Cebu, Lapu-Lapu City and Mandaue.
Almost 100,000 voters were added in the province during the registration last year, Lambino said.
Cebu had 2.4 million registered voters in the May 2010 elections.
"Cebu remains the number one richest voting population in the entire Philippines," Lambino said.
Lambino said this could be the reason politicians often visit Cebu during the election season.
Cebu Provincial Comelec Supervisor Lionel Marco Castillano said people from the provinces in Central Visayas and Mindanao come to Cebu because it is more accessible when seeking economic opportunities than Manila.
He said there are more migrants who often come to look for jobs and business opportunities in Cebu.
"Many local government units require those asking for business permit to be a registered voter," Castillano said.
He said Cebu is densely populated, and 50 to 60 percent of the 4.5 million people are registered voters.
The number of voters in Cebu reached more than half of the total registered voters in the Central Visayas, which is 4,114,061.
It increased three percent compared to the three million registered voters in the region in the past elections.
Based on the records of Comelec 7, Bohol has 775,785 voters. Negros Oriental has 763,938, while Siquijor has 64,818, the province with the least voting population.