According to E! Online, the Australian actress is now pregnant with her second child with her partner.
Byrne's upcoming film projects include starring in Will Gluck's Peter Rabbit and Jesse Peretz's Juliet, Naked.
"I'm a little exhausted but feeling good", Byrne told Jones. She dropped the news super casually, as one does.
The actress added that she leans on her mother and father for advice.
The couple confirmed the happy news to Jones magazine - fashion giant David Jones' new print offering - telling the publication of their excitement. "Everyone was very sweet on set today, and you always get a little bit more attention when you're pregnant, which is fabulous", she said half-jokingly.
Wearing an elegant red polka dot dress, the Australian actress looked glowing in a photoshoot for the magazine, as she excitedly discussed her baby news.
The couple, who maintain a relatively low-key relationship, became more open after Cannavale gushed over Byrne in his 2013 Emmy speech for Outstanding Supporting Actor, saying, "And I want to thank the love of my life, Rose".
Rose has previously spoken about how she struggled to leave the house when Rocco, who is named after a French saint, was three-months-old.
Byrne spoke about motherhood last summer in Australia's Daily Telegraph (Byrne, an Aussie, clearly saves all her best sound bites for her native country's media outlets). I'm done, I'm going back in.
Rose recently claimed she is "thrilled" to be doing a movie her young son can enjoy - and now baby number two can be part of the fun. "I also like to think Rocco has brought out better qualities in me".