The pair has been close since shooting to fame on hit comedy 'That 70s Show', and sparked rumours they are dating in April.
The stars have yet to comment on the speculation, but kept the rumour mill going when they hooked up for a date at Soho House in LA.
The pair was snapped cuddling and flirting as they enjoyed drinks, reported Us magazine.
"They were seated on a couch on the same side of the table and Mila was running her hands through Ashton's hair. She had her elbow resting on his back and couldn't stop playing with his hair and rubbing his shoulders. He leaned in and whispered to her and kissed her cheek. They were holding hands," a source said.
