"They were making out at Soho House," an eyewitness told the publication. "They were all over each other for a lot of the night."
Jimmy Kimmel's ex-girlfriend and the Master of Sex star were seen at Sheen's 45th birthday party in West Hollywood. Also in attendance at the event were his costar Lizzy Caplan, Nicole Richie, Kate Hudson, Demi Moore and his ex-wife Kate Beckinsale.
"Sarah and Michael came and left together. She drove," an insider told UsWeekly. "When they left, Sarah opened her trunk so Michael could put all of his gifts in and then they drove away."
Sheen was married to Beckinsale for eight years before the pair divorced in 2003. They have a 14-year-old daughter named Lily. Since his divorce, the actor has been linked to Carrie Keagan and his Midnight In Paris co-star Rachel McAdams. Silverman dated Kimmel for five years before the two split in 2009.