Chen, who co-founded the site in 2005, actually left the company last autumn, but it has only just confirmed his new focus of responsibilities at Google, following reports in the US of Chen's departure.
A spokesman for Google said Chen would still be involved in YouTube.
His role as chief technical officer at YouTube will not be replaced and his responsibilities have been shared among other technical directors within the company.
In his new role, Chen will be will responsible for a range of engineering projects, although he currently does not have a job title.
Google bought YouTube in 2006 for $1.65bn, but the site has since struggled to make a profit.
Chen, co-founder and technical chief, launched YouTube with current chief executive Chad Hurley, and Jawed Karim, who left the business soon after it was established.
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