The actress, 38, and husband David Bugliari -- Milo Thomas Bugliari (boy), on Wednesday. Later that day, the actress took to Twitter to share her joy.
"Thank you for all the well wishes for my son Milo,my heart has tripled in size. I love him more than all the leaves on all the trees."
This is the first child for Milano and Hollywood agent Bugliari, who wed in 2009.