In the year to March 2009, Millicom International Cellular said its Sri Lanka subscribers grew 54 percent to 2,111,295.
Other players in the market include, Hutch and new entrant Bharti Airtel which launched services in February 2009.
Hutch saw subscribers fall last year under tighter classification rules.
Updated Mobitel said profit after tax fell 17 percent to 250 million rupees in the March 2009 quarter against 301 million rupees a year earlier.
Mobitel led the price cuts in the telco sector with its Upahara branded package aimed at state workers.
"Revenue recorded a steady growth of 48 percent despite price erosion as a result of the rapid growth in the subscriber base and initiatives undertaken by the company to drive usage," the firm's parent, SLT said in a statement.
Mobitel was now the market leader in the post-paid segment, the statement said.
The company said earnings before interest tax depreciation and amortization (EBITDA) was up 25 percent