Richards tweeted she shared a "nice mellow dinner" with the actor at Da Tommaso Italian restaurant in Manhattan's theater district Thursday night.
The pair, who were married from 2002 to 2006, have been spotted together recently as Sheen, 46, recovers from the highly-publicized drug-and-alcohol-fueled meltdown and ouster from his hit "Two and a Half Men" sitcom earlier this year.
Richards has said that the flagrant partying on display during Sheen's downward spiral did not represent "the person that I met and fell in love with."
"The man I fell in love with is very compassionate, humble and has a very wonderful heart," she said in a "Today" show interview in July.
Richards, 40, is in New York to film a guest role on NBC's "30 Rock."