Widodo, in a repeat of the 2014 election, is running against former army general, Prabowo Subianto, for a second five-year term in office.
“For the young, the women, and the men, we will make sure that our lives are better than today in five years’ time,” Widodo said at a rally on Saturday.
With more than 190 million eligible voters and 800,000 polling stations, Wednesday’s presidential and legislative elections will be one of the largest displays of democracy in the world.
This will be the first time that the presidential vote will be held on the same day as elections for seats in the House of Representatives.
Al Jazeera’s Wayne Hay, reporting from Widodo’s rally, said: “The huge crowd here is an example of how big and complex the democratic process is in Indonesia.”
Subianto, who held his last rally on Friday, was beaten in a close race in the elections five years ago.
He has trailed in most pre-election polls during his campaign, but has closed the gap in recent weeks.
“There are still a few days until the election,” Subianto said. “Hopefully we can easily overtake the other candidate. Ladies and gentlemen, together we will realise a fair and prosperous Indonesia.”
Both candidates have talked about uniting a country that has becoming increasingly divided along conservative and moderate religious lines.