Zach popped the question to his girlfriend on Wednesday, and according to People, he wrote on his Facebook page, "She said yes!
"It's been a brilliant 24 hours and totally excited for what the future holds."
Zach, 23, reportedly proposed to Tori, 22, in a grassy open field and his brothers Jeremy James Roloff and Jacob Roloff took "romantic pictures" of the event.
Ironically, Jeremy, 23, just got engaged to his girlfriend Audrey Mirabella Botti in March. That same month, Little People, Big World stars Amy Roloff and Matt Roloff -- who are the parents -- announced their surprising separation after 26 years of marriage.
"I couldn't be more proud or more overjoyed w/ my two sons Jeremy and Zachary," Amy wrote in a Wednesday Facebook post.
"They've chosen a wonderful woman and asked them to be a part of their life and join them on the rest of their life journey. They said Yes! I'm excited to have Tori and Audrey a part of the family -- Love Love."