The 22-year-old daughter of the late Steve Irwin shared the news with her social media followers on Tuesday, Sept. 22.
"Baby girl, you are our world," Irwin wrote on Instagram. "Our beautiful daughter is now about the same size as a hatchling Aldabra tortoise and is as healthy as can be. We can't wait for her arrival next year."
Alongside the announcement, Irwin posted a sweet photo that showed her hugging a giant tortoise and Powell holding a sonogram. The father-to-be also shared the baby news on his Instagram page on Tuesday.
"Our little girl and my beautiful wife are my entire world," the 23-year-old wrote. "I'm so excited to meet our daughter when she's born next year and to see the incredible person she will grow up to be."
The couple, who tied the knot in March, announced their pregnancy news over the summer.
"Baby Wildlife Warrior due 2021," Irwin wrote on Instagram in August. "Chandler and I are proud to announce that we're expecting! It's an honour to share this special moment in our lives with you."
"Though I'm still in my first trimester, we really want you to be part of our journey from the beginning of this new life chapter," she continued. "We couldn't wait to share the news as this beautiful little being has become the most important part of our lives. Your support means the world to us."
Powell also wrote to his social media followers at the time about the couple's new chapter. "Becoming a dad is the highlight of my life," he shared. "I cannot wait to embark on this new adventure and life chapter with my gorgeous wife, @bindisueirwin. Bee, you're going to be the most amazing mother."