The multinational company, based in northern Spain's Bilbao, said that net profits rose to 3.01 billion euros last year, an increase of 7.5 percent on the 2017 profits and the first time the company had passed the 3 billion-euro benchmark.
2018 saw Iberdrola's revenue climb from 31.26 billion to 35.08 billion euros, while earnings before interest, taxes, depreciation and amortization increased from 7.32 billion to 9.35 billion euros.
The company put the increase in profits down to the fruits of its investments made in renewable energy in recent years, along with growth in Latin America and a recovery in hydropower in Spain.
In a report, the company informed it had capital expenditure of 5.32 billion euros in 2018 to take "total investments" to "20 billion euros over the past four-year period."
It explains it will continue this investment with "6,606 MW (megawatt) renewable capacity, and 3,508 MW in new gas combined-cycle plants" -- all currently under construction.
"The profits that we have obtained make clear the success of a sustainable model and will inspire us to continue working for the transition towards a low carbon emission economy," said Iberdrola President Ignacio Sanchez Galan.