The Internet is expected to contribute around $18.8 billion -- 7.2 percent of the total -- to Hong Kong's economy by 2015, driven by a surge in mobile use and online shopping, a report for Google said.
The digital market in the city of seven million stood at HK$96 billion ($12.4 billion) in 2009, or 5.9 percent of its gross domestic product for the year.
It is projected to grow by an average 7 percent every year to reach an estimated HK$146 billion ($18.8 billion) by 2015, said the report, entitled "The Connected Harbour: How the Internet is transforming Hong Kong's economy".
"The anticipated growth rate of the Internet economy is considerably faster than Hong Kongs forecasted GDP growth rate of 4 percent," said the report.
It said the growth will be led by increased consumer spending on online shopping and deeper mobile penetration, which will drive online consumption. Hong Kong's broadband penetration ranks sixth in the world.
The report, written by Boston Consulting Group and commissioned by Google Hong Kong, evaluated the city's Internet economy through an index based on broadband subscriptions, smartphone adoption and online consumption.
The index ranked Hong Kong ahead of Singapore and on par with the United States and Luxembourg but behind Korea, Japan, Britain and Germany.
The report said about a third of the city's Internet economy comes from consumption, another third from net exports of Internet-related hardware and e-commerce, and the rest from government and private investment in Internet-related goods and services.
The report also found most small and medium-sized enterprises that actively use the Internet achieved higher sales.
The government has welcomed the findings, saying it showed "strong indicators" of the vibrancy of Hong Kong's digital economy.
Explore further: Twitter takes note of other apps on smartphones