Speaking in London last night at the opening ceremony of Europe's biggest technology festival, Campus Party Europe, Kroes said attitudes in the industry need to change.
Last year a report from the National Centre for Women and Information Technology found only 20% of people working in the technology industry were female - with no change in the past 15 years.
Kroes, who is also European commissioner for the Digital Agenda, the EU's technology strategy, said: "It all begins with education and convincing girls this is a viable career.
"The problem is too many girls don't believe a career in technology is sexy enough.
"We need to push our young female talent and make them believe they can succeed in this industry."
Glastonbury for geeks
Also speaking at the event, described as "Glastonbury for geeks", was UK communications minister Ed Vaizey. He said it's vital to change the sector's "boys with their toys" image, but added a lack of female talent is not just a problem faced in the technology sector.
"If you're not making your workforce female-friendly then you're cutting off a large pool of talent," he said. "Technology should be at the forefront of this issue and be embracing diversity."
Kroes also called on Vodafone to invest some of the $130 billion it will receive from selling its 45% stake in Verizon Wireless back into the industry, to help "harness" young female talent.
Finding talent
The five-day Campus Party Europe festival aims to promote digital skills and help entrepreneurs get their ideas off the ground. It will focus on areas including robotics, gaming, social media and astronomy.
Telefonica CEO Ronan Dunne said this type of event is crucial to inspire a new generation. "It will help people hone and develop their digital skills while giving businesses of all sizes the opportunity to find the talent they need to grow," he said.
O2 estimates around 10,000 people will visit the site during the five-day festival.
