The star hopes the image will inspire other new moms, saying:"Being shot with Otis is so perfect because any portrait of me right now isn't complete without my identity as a mother being a part of that. Breastfeeding is the most natural thing... It feels like Otis should always be on my breast.
"It felt like we were capturing that multifaceted woman we've been discussing - that we know we can be. You can be someone who is at once maternal and professional and sexy and self-possessed. I mean, I certainly don't really look like that when I'm (usually) breastfeeding."
Wilde does look rather glamorous in the shot in which she's sitting at a booth in a diner wearing a fancy dress and heels.
The actress and her fiance Jason Sudeikis welcomed their son at the end of April but haven't started planning their wedding just yet.
She explained: "We're engaged, but no specific plans yet. We just have to find the time to put it together. In many ways, a child is more of a commitment. We are fully committed and really happy as a family... I don't feel any pressure to do it (marry). But I think it will be really fun."
Wilde stars in the 2015 film "Lazarus" about a group of medical students who discover a way to bring back the dead.