The couple shared the news on social media on Monday.
"Extremely blessed and grateful to say that @stellamcyrus and I are expecting our first child," Braison, 26, wrote on Instagram. "This is our son and he’s due in June. Love this little dude so much already."
The accompanying photo showed the dad-to-be posing with ultrasound images of his little boy, while Stella smiled and cradled her baby bump.
The couple snapped the joyous pic in front of a Christmas tree.
Braison, a musician, actor and model, also posted a close-up photo showing the baby boy's head in the sonogram, and a video showing the baby's heartbeat on his Instagram stories.
Miley, 28, was thrilled to hear the news, commenting, "Aunt Swinkle in the [house]," on Braison's post.
Stella also took to social media, sharing her excitement about receiving "the greatest gift of my life" amid a trying year.
"2020 has been a difficult year to say the least, but it has also brought me the greatest gift of my life!" she wrote. "I cannot wait to meet our baby boy this summer and watch him spread light & happiness to those around him. You’re going to be the best dad ever @braisonccyrus 🤍."
She then shared the sonogram on her Instagram stories, writing, "I mean I know I'm his mom, but I'm pretty sure this is the cutest thing to ever exist."
Braison and Stella tied the knot in November 2019.
"My baby brother got married on the most stunning sunny Tennessee day standing on top of the same hills where we grew up playin," Miley wrote on social media at the time. "I love you Braison. So happy for you & Stella."
See more on celebrities who are expanding their families during the coronavirus pandemic below.