The Swedish utility said the increase was down to the addition of 570MW of wind capacity in the first half of the year.
This includes the completion of the 288MW Sandbank offshore project in Germany and the 228MW Pen y Cymoedd onshore site in Wales.
Generation from Vattenfall's wind fleet therefore increased from 2.8TWh in H1 2016 to 3.9TWh this year.
Across the whole Vattenfall group, underlying profit increased from SEK 12 billion (€1.3 billion) to SEK 13.2 billion (€1.4 billion), while profit for the period increased almost six-fold from SEK 1 billion (€104 million) to SEK 5.9 billion (€616 million).
Much of that profit was due to the sale of the company's sale of its lignite business.
"I certainly think that things now look much better, but there is no time to relax. Instead we need to put more effort into things: our result and finances are more stable now and it is a good platform for us to go forward," said CEO Magnus Hall.
Vattenfall's CFO Stefan Dohlern added: "Our finances are now more stable. This development has also been acknowledged by the rating agencies who have therefore changed their outlook from negative to stable in their recent rating reviews."
Earlier this month, Vattenfall announced a reorganisation of its wind division, splitting it in to three sub-units concentrating on onshore wind, offshore wind, and photovoltaic solar and storage.