Nielsen, the research firm, reported that 48% of the country's online audience log on through wireless handsets, and an additional 13% employ alternative portable multimedia devices.
Looking ahead, an extra 5% of netizens expressed the intention of engaging in this pastime for the first time on a phone in the coming 12 months, reaching 17% for equivalent gadgets.
"All indications suggest certain and significant growth of Internet access using mobile phones and other handheld devices over the next 12 months and beyond," said Irawati Pratignyo, managing director, media, for Nielsen Indonesia.
Elsewhere, some 36% of Thailand's connected community surf the net from a mobile, measured against 35% for Singapore and 29% regarding Vietnam.
Scores here hit 24% concerning the Philippines and 21% when assessing Malaysia.
However, overall penetration remains low in Indonesia, standing at 21% of people in the 15-49 year old demographic, considerably below the regional average of 38%.
Singapore topped the charts on these terms, registering 67%, with Malaysia achieving 38%, the Philippines securing 33%, and Thailand posting 31%.
Two-thirds of Indonesians stated internet cafes were the most common location from which they went online, whereas a similar number generally did so at home throughout South East Asia as a whole.
Indeed, only 19% of Indonesians currently have a home connection, Nielsen said.
"Phones and tablets offer easy access to the internet for many Indonesians without having to rely on broadband services at home," said Pratignyo.
