"This is the most important time for Thailand," he said, adding that he was excited to see that so many people had registered to vote in advance.
More than 52,000 people registered to vote in advance of the May 14 general election at Ramkhamhaeng University.
Advance voting is taking place today across Thailand.
Chadchart also urged officials at the polling station to do their best to facilitate voting and follow procedures for verifying the eligibility of voters.
The Bangkok Metropolitan Administration deployed medical staff and water trucks to polling stations to help voters cope with the heat, Chadchart said. The administration has also prepared a highly secure place to safeguard early-voting ballots, he said.
Chadchart also asked people to be vigilant for any election irregularities, but added that no complaints about corruption in the election had been received so far.
Election Commission secretary-general Sawaeng Boonmee also visited the polling station to oversee the process.
The three polling stations with the highest number of registered advance voters in Bangkok are Ramkhamhaeng University with 52,711, followed by Siam Paragon in Pathum Wan district with 40,787, and Huai Khwang district office with 28,344.