Significant one-off and non-cash impacts in the previous year, relating to costs and significant impairments from taking direct control of international geothermal investments in Chile and the United States largely accounted for the boost in year-on-year lift in net profit.
After adjusting for these impacts, underlying earnings were up 3 per cent or $5 million.
Mighty River Power chairwoman Joan Withers, said generation from low cash cost renewables provided the foundation for delivering above the IPO forecasts.
Chief executive, Doug Heffernan, said the company's differentiated retail electricity brands performed well as competition continued to intensify across all residential and business segments.
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He said the rate of switching from retailer Mercury Energy was 2 per cent lower than the market average.
Withers said the performance against the IPO forecasts, along with lower capital expenditure in the past financial year meant that the board saw it as appropriate to declare an increased final dividend of a fully-imputed 8.3 cents (up 0.5 cents on the IPO forecast) to be paid to shareholders on September 30.
The company expects earnings in the 2015 financial year to be in the range of $495 million to $520 million - subject to any adverse events, significant one-off expenses or other unforeseeable circumstances including hydrological conditions.
Mighty River Power shares listed at $2.50 last year and yesterday closed at 2.37.5c. They have traded as low as $1.94.5c in the past 12 months.
See Mighty River's latest financial results presentation here: