"Most people know we dated for a little bit. I'm very happy for her. She seems like she's happy," Joe, 36, said on Thursday's episode of his "Click Bait with Bachelor Nation" podcast, which he co-hosts with Natasha Parker and Tia Booth.
"It seems like they are each other's person. So yeah, good for her," added the former grocery store owner from Chicago.
"We're engaged!!" Kendall captioned a photo of the couple kissing and embracing after the marriage proposal.
"It's always been a HECK YES with you Mitch. I love your brain, I love your family, I pretty much just love every single thing about you! So incredibly over the moon that we get to start our epic adventure together in a new country."
Kendall announced in late October that she's moving to Germany with Mitch after repeatedly refusing to even give Chicago a chance with Joe, which resulted in the former Bachelor in Paradise couple splitting up.
Kendall continued in her Instagram post, "I've heard love explained to me by my parents and was scared I would never experience something so wonderful. But with you, love is so much better than I could have ever imagined it to be."
"I feel so lucky and I can't wait to officially be a Sagely," she concluded.
Kendall, who appeared on Arie Luyendyk Jr.'s season of The Bachelor followed by multiple seasons of Bachelor in Paradise, and Mitch, an aerospace engineer, met through mutual friends in December 2021.
Mitch asked Kendall to be his girlfriend on Valentine's Day in February 2022, and then Kendall went Instagram official with Mitch in April and bragged about how she was "in love."
Joe, who competed on Becca Kufrin's season of The Bachelorette as well as Dancing with the Stars, currently lives in New York with Serena and they are planning a big wedding for their family and friends to attend in 2023.
Kendall and Joe fell in love on Bachelor in Paradise's fifth season in 2018, and then they moved in together in Los Angeles in April 2019.
Kendall and Joe attempted to remain friends after calling it quits in 2020, but Kendall previously explained their breakup was difficult for her because they never fell out of love; it was logistics that broke them apart.
Kendall said she wanted to continue living in Los Angeles, CA, where her family and friends are, but Joe hoped to move back to his hometown of Chicago to be near his loved ones.
"What happened was we broke up, we fought... we had our differences... but then I came back to [Los Angeles] four months after and I was pushing to have that conversation," Joe recalled on Bachelor in Paradise last summer.
"You were pushing to have me move to Chicago," Kendall argued with Joe.
"I was pushing to have you try -- yeah," Joe clarified, "to come move to the city where I grew up in, where my friends and family are. I think if you just would've tried, we could've figured something out."
Kendall said things probably would've ended the same way regardless because she had made it clear from the start of their relationship that moving away from her hometown was "a dealbreaker" for her.
"I wasn't going to change my mind and I think you were hoping I would," Kendall said on the show last year.
"Your thing was that you didn't want to move anywhere for a man... I should've been more than just 'a man' at that point, and we could've tried it," Joe pointed out.
Once Kendall and Joe worked through a "messy" reunion and found the closure they needed, Joe pursued a relationship with Serena on Bachelor in Paradise.
"If she really wanted me back," Joe said of Kendall on the ABC reality series, "she should have told me before I got here and before I started this. Because I really, really loved her."
Kendall ultimately decided to quit the show because she said it was too difficult to watch Joe with Serena and her feelings for Joe registered as painful realizations that she wasn't over him. She didn't want to sacrifice her mental and emotional well-being to stay on the show.