Fauzi Bowo -- the wealthy incumbent who counts an original Van Gogh painting among his possessions -- faces a field of five other challengers, including Joko Widodo, the popular mayor of Solo city in Central Java province.
Opinion polls predict the contest will be a two-man race between Widodo and Bowo, the favourite who is backed by President Susilo Bambang Yudhoyono's ruling Democratic Party.
Southeast Asia's most populous city -- where modern skyscrapers often rise above slums and shantytowns without piped water -- is weighed down by corruption, and a bare-bones public transportation system.
At least 1,000 new vehicles are added every day to about eight million already on the roads, where street children and beggars knock on the windows of cars that barely-move during rush hour.
According to the private Indonesian Transportation Society, traffic in the capital of the world's largest Muslim country is destined to turn into a massive gridlock by 2014.
Most people in the capital -- whose official 10 million population doubles with migrant workers on weekdays -- get around in jam-packed buses.
Voters, enjoying a public holiday declared for the election, said they hoped the incoming governor would help solve some of their most pressing problems during his five-year term.
"I'm going to vote for Joko because I want to see changes," parking attendant Supriyatna, 35, told AFP.
"Bowo promised an MRT (city railway network), no flooding, no jams. There's still no MRT, I still walk around in knee-deep floods whenever it rains. I'm always late for work because of the traffic. These must stop."