He will start his role on 1 June, replacing longstanding media director Jon Church, who is moving to Australia in July to work for retailer Coles.
Datson is the second high profile PRO to leave Cadbury in the past few weeks following the Kraft takeover. Cadbury global corporate affairs director Alex Cole left in March.
Datson was previously head of corporate media relations at Tesco before he became external comms director in Danone in 2008.
He will report to Tesco executive director corporate affairs Lucy Neville-Rolfe. She said: ‘I'm delighted that Trevor is rejoining Tesco. He brings with him a wealth of experience in the media, consumer and financial industries and knows Tesco well from his previous time with us as head of corporate media.
‘I'm also sorry to see Jon Church go but wish him and his family well as they emigrate to Australia to live and work. He has done a great job over the past nine years, a decade in which media interest in Tesco has grown hugely, and we will miss the cheerful and populist approach he has brought to communicating our business and its strengths."