Tomlin who oversaw the recruitment of 70,000 volunteers for the London Olympics will replace outgoing former newsreader Anna Ford.
Previously Tomlin has been HR director at Marks and Spencer and internet bank Egg before taking up the same role for the London organising committee of the Olympic and Paralympic games.
Tomlin will chair Sainsbury's corporate responsibility committee and will also sit on the remuneration and nomination committees.
Tomlin will join on 1 January following the retirement of Ford, who has been on the retailer's board since 2006. She took up the £68,000-a-year role after a 30-year career at the BBC, which included stints on Tomorrow's World and Radio 4's Today programme, before fronting the One O'clock News.
Sainsbury chairman David Tyler said: "We're delighted to welcome Jean to our board. Her unique experience and breadth of skills will be a great addition."
Tomlin added: "Sainsbury's has an outstanding reputation and, with 22 million customers and 150,000 colleagues, touches so many areas of day-to-day life. I very much look forward to playing my part in the company's progress."
