PacNet started its roots as TechNet (TechnologyNet), a closed research and development computer network set up for academics’ use at the National University of Singapore (NUS) in 1991. It was set up by the National Science and Technology Board of Singapore (NSTB) then.

In 1995, the Sembawang Group, a diversified Singapore conglomerate, planned the introduction of internet access in Singapore and the Asian region after noting the significant progress made in the US in this industry. Through its subsidiary, SembVentures (now called SembCorp Ventures), SembMedia, a holding entity that experimented with a number of Internet startups, was born. SembMedia bought TechNet, an academic division of the National University of Singapore, which owned an Internet access license, and commercialized its services in September 1995 when it launched Pacific Internet Corporation Pte Ltd.

In line with the Pacific Internet's strategy to expand regionally, Pacific Internet established its presence in Hong Kong in June 1996 after acquiring a 50.1% interest in Sembawang PacMann Pte Ltd., the holding company of Pacific Supernet Ltd. Pacific Internet further increased its stake in Pacific Supernet to 100% in June 1999. The Group commenced its Philippines operations in September 1997 and formally acquired its 40% equity stake in Primeworld Digital Systems, Inc, in March 1998. Pacific Internet's Australian operations started with the acquisition of Mira Networking and Zip World in May and June 1999.

By March 2000, further acquisitions of Australian ISPs brought the Group's presence to six major cities in Australia. Pacific Internet India, a joint venture unit of Pacific Internet Ltd, was launched in December 1999, and currently operates in Mumbai, New Delhi, Bangalore and Pune. In January 2000, the Group acquired World Net & Services to mark its entry into the Thailand Internet market, and officially launched Pacific Internet Thailand in June 2000. To date, the Group operates as an ISP in six major Asian countries - Singapore, Australia, Hong Kong, India, The Philippines and Thailand.

Pacific Internet launched its initial public offering of shares on 5 February 1999 on NASDAQ, at a price of US$17 per share. The Company raised approximately US$35.3 million in net proceeds which was used to finance acquisitions, capital expenditure and other general corporate purposes, including working capital. On May 20, 1999, Pacific Internet and its major shareholders, SembCorp Ventures and SIM Ventures, sold a total of 2,125,000 shares at a price of US$51.4375 per share as a second offering. The Company received total net proceeds of approximately US$10.4 million on May 26, 1999.