In this newly created role, Williams will report to Clare Broadbent, chief executive officer of Cedar.
The restructure also includes the creation of an executive board and the strengthening of the management leadership team.
Williams has been at Cedar since 2007 and worked on a variety of accounts. For the past 18 months, she has been group account director for Tesco.
During this period, she launched Tesco Real Food, which Cedar claims is the UK's largest food title with more than two million readers. It has complementary content platforms, including an advertising-funded television programme, its own social media programme, a website and ezine programme.
She was part of the senior team which successfully pitched for Tesco Lifestyle in China and then went on to set up Cedar Shanghai.
Also joining the management leadership team are Maureen Rice, previously editorial director and now editor in chief; James Mastin, the international client services director, and Karen Huxley, group account director for British Airways.
Williams said: "Cedar has seen two years of double-digit growth, despite the recession. We have expanded our international network, mastered new content channels, brought on many new clients and expanded our in-house expertise on every level.
"Cedar is an exciting place to be, with a unique commercial offering that is proving attractive to a growing number of partner companies. I am excited about the upcoming plans we have for both our clients and Cedar, across all our offices in UK, China and South Africa."
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