Opposition to the pageant in the world's most populous Muslim-majority nation has intensified in the past week, with demonstrators and some officials calling for the event to be scrapped.
Organisers have already dropped the contest's famous bikini round but the move has failed to appease hardliners and protests have been growing, with today's the biggest yet.
Some 800 men and women from the Hizbut Tahrir Indonesia hardline group gathered in Jakarta outside the social welfare ministry, calling for the government's support to cancel the show.
"Do we want our country to be seen as the most pornographic?" one protester shouted.
"We are going to keep rallying to tell people how degrading this event is to women," protest organiser Zikra Asri told AFP, surrounded by women in Islamic headscarves and loose black dresses.
In Medan city on the island of Sumatra, another 500 members of Hizbut Tahrir marched to government buildings, demanding the event be scrapped.
The Miss World contest begins Sunday on the resort island of Bali, where the majority are Hindu and women sunbathe on beaches in skimpy swimwear with little fear of causing offence.
The winner will be crowned on the outskirts of Jakarta on September 28.
While most Indonesians in the nation of 240 million people practise a moderate form of Islam, a vocal hardline fringe has succeeded in getting events cancelled in the past.