The company forecast revenue of at least $400 million for fiscal 2009 compared with $251 million for 2007/08, which it reported on Monday.
iiNet also reported a 12 per cent rise in full-year net profit from continuing operations to $19.9 million, from $17.8 million a year earlier.
The previous year's actual profit was $23.3 million, with contributions from the now discontinued New Zealand operations.
Managing director Michael Malone said the company planned to make further acquisitions after buying Australia's sixth largest ISP Westnet for $81 million.
iinet was forecasting synergy savings of $2.5 million through the acquisition of Westnet.
iinet has worked to raise margins by moving customers to products based on the company's own network rather than reselling Telstra Corp Ltd's wholesale offerings.
"The main reason for the gains in profit are because we got more customers onto our own network," Malone told reporters.
"We think the market wants an alternative to Telstra and we can offer customers a higher speed and better quotas for the same price."
iinet has $24.7 million of free cashflow for acquisitions or other growth opportunities.
Earnings before interest, tax, depreciation and amortisation (EBITDA) grew by eight per cent to $49.5 million compared with the company's forecast of $46 million, iinet said.
Shares in iinet closed two cents lower at $1.68 but had fallen as low as $1.64.
Malone said the company would be working to move Westnet customers, who were all on Telstra wholesale products, across to the iinet network.
"We are delivering on our commitment to be the leading innovator and challenger in the Australian telecommunications market," Malone said.
iinet was committed to innovation in the telecommunications industry through products such as Naked DSL, which offers ADSL 2+ speeds of up to 24 megabits a second (Mbps) without requiring customers to rent a fixed phone line.
iiNet has more than 30,000 naked DSL customers.
The company will pay a final dividend of four cents a share, taking full-year dividends to seven cents, fully franked, compared with six cents the year before.
The company has net debt of $24 million, with a net debt to equity ratio of 13 per cent.
Westnet brought 215,000 phone and internet subscriptions, raising iiNet's total subscriber numbers to more than 680,000, and the company now covers 30 per cent of the Western Australian market.
