The actor is yet to share the news on his own social media, but his Riverdale co-stars were quick to share their congratulations on the post.
Co-star Lili Reinhart, who stars in the show alongside Apa, wrote, "Can't wait to meet him, congratulations".
Another co-star Vanessa Morgan wrote, "River's new bestie!"
The couple have reportedly been together since the summer of 2020, first announcing the news of their pregnancy in May this year.
His stunning girlfriend had shared a photo of her baby bump on social media.
"She's pregnant btw," Apa commented on her Instagram post.
His Riverdale castmate Vanessa Morgan congratulated the couple on the news, saying the child will be a "bestie" to her own child River.
The couple first went public with their relationship in February, and Apa posted intimate photos of Berry last October displaying his affection for the model.
"There's nowhere else," Apa wrote in the post's caption.
The actor made his relationship with Berry Instagram official last year by posting a photo of them kissing, with the cryptic caption "coupe de foudre", which according to Seventeen translates roughly to "love at first sight".
Eagle-eyed Riverdale fans first speculated about the couple's romance after spotting they were liking each other's Instagram photos. Apa let slip he was in love during an interview with Wired.
During the interview posted to Wired's YouTube channel, he answered the web's most Google-searched questions about him, revealing that he was "very much in love".
The 23-year-old actor has played Archie Andrews on the sci-fi teen show Riverdale since 2017. Prior to making it big in Hollywood, he kickstarted his on-screen career playing Kane Jenkins on Shortland Street from 2014-2015.