"OMG OMG OMG," she gushed alongside a photo of the future husband and wife. "Ellie and Mark are engaged!"
"And she's wearing the ring her Dad gave to me," Couric wrote, alongside a slew of happy hashtags.
"I had never had something horrible happen to me before. Jay used to say I was born on a sunny day, and suddenly I wasn't," Couric told PEOPLE Editor-in-Chief Jess Cagle last year. "Like the clichés say, it made me appreciate things. It made me understand how important it is to say things in the here and now and not wait. When someone is important to you or means something to you, you need to tell them and not wait."
"It's also, I think, most profoundly given me a higher sense of purpose that I'm in a position to take this unimaginable pain and loss and try to do something positive with it," she added.
Couric went on to marry banker John Molner on June 21, 2014 at her private home in the Hamptons.
"It took me a long time [to marry again] because I loved being married and I love being married now," Couric told Cagle. "And I'm not a solitary person. I like company. And John is so funny. He's just got this incredibly dry and wry sense of humor, and he doesn't take himself too seriously. And he's just fun to be around."
"Sometimes we get angry at each other. Sometimes I feel like he can be tough and I'm sure he thinks I'm insane," she continued. "But for the most part, he's really good company, you know? And I can totally be myself with him, sometimes maybe to a fault."