The stars were spotted enjoying a romantic stroll along the Champs-Elysees early last week (begs12Sep11), before they returned to the U.S. last Wednesday (14Sep11) - the same day the Hollywood beauty found herself at the centre of a nude photo scandal.
Steamy cellphone shots of the curvy Lost In Translation beauty surfaced online, and she is reportedly working with FBI agents to track down the culprit who hacked into her mobile and distributed the images.
If the romance reports are true, Johansson, 26, and Kieran Culkin, 28, will have plenty to talk about - they attended the same high school in New York.
Johansson split from ex-husband Ryan Reynolds in December (10) and ended a fling with Sean Penn earlier this year (11). She has most recently been linked to Justin Timberlake, although insiders insist the celebrities are just good friends.