Charlize – who split with her actor boyfriend Stuart Townsend earlier this year – and Keanu shared a series of kisses and hugs outside a restaurant.
Monster star Charlize also appeared to have her hands around Keanu's back, under his jacket.
When the pair noticed they were being photographed they quickly moved away from each other, however.
US website TMZ posted a video of the couple getting smoochy after their dinner date.
Fans of Keanu will no doubt be hoping he has found happiness at last. The actor has talked of his desire to marry and have children in the past, but his life has been touched by tragedy.
His girlfriend Jennifer Syme was killed in a car accident in April 2001, two years after the couple's baby was stillborn.
If reports of a romance with Charlize do turn out to be true, it will be a case of life imitating art.
The pair played on-screen lovers in 2001 tear-jerker Sweet November (pictured). They they were also husband and wife in 1997 movie Devil's Advocate, in which they appeared with Al Pacino.