The smitten couple could hardly keep their hands off each other during an outing in downtown New York.
Smooching in the street, they were clearly making the most of being reunited after a couple of weeks apart while Carey has been away on the awards circuit.
The An Education actress, who picked up a Bafta last month, started dating Shia after they were introduced last August by director Oliver Stone.
This was just before they started filming the Wall Street follow up Money Never Sleeps.
They embarked on the romance against the advice of co-star Michael Douglas who told them never to date someone you're filming with. "I warned them, 'Don't ever do that", but they are an item and they are having a great time," he said.
Carey is due to leave in a few days to attend the Oscars, where she is up for the Best Actress trophy. It's not known whether her 23-year-old beau will be accompanying her however – they are yet to attend a red carpet event together.