Marissa Mayer, Yahoo CEO

Yahoo has named Google executive Marissa Mayer as its new president and CEO.

Mayer will replace former boss Scott Thompson, who left Yahoo just months after taking the role when it was revealed the CV he used to land the job contained irregularities.

Mayer was one of the earliest employees at Google, joining the then start-up in 1999 after gaining a degree in computer science from Stanford University. She started at Google working on the user interface of many of its products.

She was also vice president of search products and user experience and more recently was heading up the company’s location efforts, which included products such as Google Maps and Google Earth.

Yahoo said Mayer’s appointment will signal a "renewed focus on product innovation" that the former internet giant hopes will "drive user experience and advertising revenue."

"I am honoured and delighted to lead Yahoo, one of the internet’s premier destinations for more than 700 million users," Mayer said in a statement. "I look forward to working with the Company’s dedicated employees to bring innovative products, content, and personalised experiences to users and advertisers all around the world."

"Marissa is a well-known, visionary leader in user experience and product design and one of Silicon Valley’s most exciting strategists in technology development. I look forward to working with her," added Yahoo co-founder David Filo.

"The Board of Directors unanimously agreed that Marissa’s unparalleled track record in technology, design, and product execution makes her the right leader for Yahoo at this time of enormous opportunity," said Fred Amoroso, Yahoo’s chairman.

Yahoo has struggled over the last few years, with a business failing to keep up with rivals such as Google and Facebook and a boardroom that seems constantly at war.

Before Thompson’s brief reign Carol Bartz was CEO. She too was dismissed, and launched a public attack on the company’s board of directors. She branded them "doofuses" and criticised the decision to fire her over the phone rather than face to face.

Mayer will begin the task of turning around Yahoo’s fortunes immediately, with her first day on the job being today. Shortly after the news was announced it was revealed Mayer is pregnant with her first child, due in October.