The 49-year-old actor announced the baby news himself on his social media sites like Twitter and Facebook, revealing the gender of the baby and when it's due.
"Yo. Susan. Me. Baby. Girl. November. Scorpio?" he posted.
Robert later posted a longer message on Facebook, "Um. I don't know if it's a 'man's world,' but I'm certain women run it. Susan and I are therefore delighted to announce we are expecting a baby. Girl. November."
The couple met on the set of 'Gothika' in 2003 and married in 2005. They welcomed their first son Exton Elias Downey on February 7, 2012.