TrustPower's annual net profit fell 6% but still came in slightly above analysts' expectations.
The electricity generator and retailer made a $123.4 million net profit for the year ended March.
Operating profit, also down 6%, was nearly $295 million. Analysts were expecting an operating profit of about $292 million.
The power company, which has the highest retail prices in the market, lost about a net 3000 retail customers a year.
Forsyth Barr analyst Andrew Harvey-Green says one of the main reasons for TrustPower's profit drop was the decline in customer numbers.
Chief executive Vince Hawksworth says part of his company's drive to retain customers includes selling them other services such as telecommunications.
He believes the company's prices are competitive and says it is still winning customers, gaining some 24,000 during the year though losing about 27,000.
Mr Hawksworth says it's a very competitive environment and there are now 15 retail companies with 22 brands in New Zealand.
"I think it's notable that we've also been able to grow our telecommunication services customers that we've sold to, and you've got to remember all of those are also electricity customers, so they're seeing some value from the bundled product that we're putting together."
Mr Hawksworth says the whole package has to deliver value otherwise the company won't retain customers.