Wearing funky '2018' shaped glasses, the couple announced the news on social media in coordinated posts on New Year's Eve.
"We're welcoming one more face to kiss in 2018! Wishing you Mas Besos in the New Year!" Ferrera, 33, wrote holding holding a tiny onesie in her hand, which read "Mas Besos (por favor)" - meaning "lots of kisses (please)".
While Williams, 36, captioned the same photo as, "Making room for new and beautiful things to come in 2018!"
The couple have been married for seven years.
Disclaimer: No Business Standard Journalist was involved in creation of this content