The Australian model and business owner shared two bump pics, tagging husband Jake Wall.
"Round two!! Jake and I are so happy to share that we are expecting a baby BOY!!!" she wrote in the caption.
Jennifer also mentioned the couple's first baby, Frankie. "We both feel really blessed and couldn’t be happier to grow our little family!
Can’t wait to see our Frankie girl as a big sis!!"
Frankie was born in October 2020 and Jennifer shares plenty of adorable videos and pics of her on Instagram.
Jennifer has spoken candidly with Marie Claire in the past about fertility struggles prior to falling pregnant with Frankie, including a devastating miscarriage and facing the possibility that she may never have children.
She's also been refreshingly honest about the way she views her body after having a baby, telling Marie Claire she now has respect for her body instead of seeing it aesthetically.
Congratulations to Jennifer and Jake (and Frankie!) - we can't wait for this little boy's arrival.