The baby's due date hasn't been announced yet, but a source told Us Magazine she's already starting to show.
"Alyssa is so excited to be pregnant again!" a source adds to Us. "She just recently started showing and has wanted to expand her family with David for a while."
Milano also announced her good news on Twitter.
♡ Ahem! Click here for some BIG, HUGE, HAPPY news☛ http://t.co/G9sxLt8XlZ— Alyssa Milano (@Alyssa_Milano) March 21, 2014
Milano and Bugliari already have a 2-year-old son named Milo.
2014: The Year in Fashion [PHOTOS]
Polly Bergen, Emmy Award-winning actress, dies