Already the proud daddy to his little girl Remi, the 31-year-old shared the incredible news on Instagram.
The former footy player posted a stunning black and white snap of his wife's pregnant belly being touched by both Beau, Kara and their four-year-old.
"Three of us, soon to be four... Excited. Happy. Blessed," the sports star wrote.
Pregnant Kara was also quick to share the news and re-grammed the same pic.
The happy news comes after a tumultuous period for the pair, showing just how much they've moved on from Beau's 2015 cheating scandal.
In September, 2015, Kara was rocked by her husband's infidelity after it was revealed he had an affair with former Hi-5 singer Lauren Brant, whom he met while working on the stage production of Aladdin.
The mum-of-one sat down with Woman's Day in early 2016 to address the scandal.
"I was actually more worried for Beau, if I'm honest," Beau's high school sweetheart confessed.
"I'm probably emotionally stronger than Beau, and I could see how upset he was, so I was more concerned for him and our family," she explained.
Adding, "I'm probably emotionally stronger than Beau, and I could see how upset he was, so I was more concerned for him and our family."
While the footy star has never confirmed the details of his relationship with Lauren, who is now expecting her first child with AFL legend Barry Hall, he did address the subject only to request privacy.
“Firstly, I just want to apologise to all the people that have been hurt recently,” Beau said during his 2015 grand final appearance on The Footy Show.
“It's been really, really hard for myself and my family, and everyone involved. But, I'm not here to talk about my private life," the father-of-one revealed.
No doubt the family are thrilled with the impending arrival of their new addition!