Shields is expected to start at the TCIO by January 2013 and will also become the Business ambassador for the Digital industries.
"Working in the UK for the past decade has proven to me that this country has the potential to become a major force in digital innovation," said Shields in a statement. "I'm thrilled to be taking this position at the Tech City Investment Organisation and proud to be a Business Ambassador for the UK for Digital Industries."
Shields also says that she believes London can be the world's best location for tech.
Prior to Facebook, Shields was President of AOL and also served as chief executive at Bebo. She was also the EMEA managing director for Google.
"I'm delighted that Joanna is joining the Tech City Investment Organisation," said Prime Minister, David Cameron. "The success of Tech City shows just what can happen when we back some of our most innovative and aspiring companies to grow, helping the UK compete and thrive in the global race. Joanna's experience will be hugely valuable in supporting Tech City as it goes from strength to strength, and as a Business Ambassador promoting the UK around the world."
The Tech City Investment Organisation was launched in April 2011 to help boosts UK trade and investment as well as support companies who want to expand into international markets.
"The UK has a creative and dynamic digital industries sector that we want to see grow even further and provide a real boost to our economy," said Trade and Investment Minister, Lord Green. "Joanna's appointment as Business Ambassador is a statement of our ambition for overseas trade in this sector and to attract new investment into British businesses."
Tech City has grown to include organisations such as Google, Cisco, General Assembly, Intel, UCL, and Imperial College London.
"The seeds have been sown in East London for a dynamic and successful cluster: we have the infrastructure, the technology and the talent, now we need to accelerate the growth," said Shields. " I am looking forward to leading the Tech City Investment Organisation in the next phase of its development. With the right boost now, there is no reason why we can't make London the number one location for tech in the world."
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