Lambeth has quit his role as editor of the Telegraph's new media technology section, Connected, and is understood to be taking up his post at AOL within weeks.
An AOL spokeswoman confirmed Lambeth had been appointed to the newly created role, but would make no further comment.
The company has no retained agency covering corporate PR, which is overseen by chief communications officer Matt Peacock. Lambeth, who joins a nine-strong comms team, will report to Peacock.
AOL UK is a division of AOL Europe, which last year beefed up its public affairs function to help roll out competitive broadband access.
This involved promoting Clare Gilbert from her role as UK policy head to European senior vice-president of public policy and regulatory affairs, to spearhead a Europe-wide PA push on the issue (PRWeek, 31 August 2001).
AOL UK hit the headlines this week when it was forced to defend the revelation that it does not have to pay VAT in the UK, because it is registered for tax purposes in the US. The tax status was revealed in a broker's report by Merrill Lynch.
In April AOL UK's parent AOL Time Warner reported the biggest loss in corporate history, taking a £37bn write-down as the dot.com slump dramatically decreased the value of its holdings. Since AOL bought Time Warner in January 2000, shares in the firm have dropped 70 per cent.