"I just want to take a second and thank this beautiful woman and her family for taking such good care of me. Not only physically, but mentally too (and I’m probably the most high maintenance patient)," Underwood captioned the shot. "She’s hardworking, passionate, understanding, kind and has the biggest heart."
Throughout his recovery, Underwood said that Randolph's family "opened up their doors to us while we were in quarantine and through everything we stuck together."
"I have made a full recovery from the coronavirus and we managed to keep the entire family healthy as well," he wrote. "I am now working with medical professionals to figure out the best way to support their efforts against the coronavirus."
"I can’t thank @cassierandolph and the entire Randolph family enough for caring for me while I’m away from my family," Underwood added.
When ET spoke with Underwood, he praised the Randolph family for their support throughout his illness.
"It's been so incredible, literally having [Cassie's mom] Amy be my little nurse and Cassie be there for me. [They have] masks and gloves on, supporting me and eating breakfast with me six, seven feet apart. And [her dad] Matt has made some killer food for me while I was recovering," he shared. "It's been as fun as you can make it in quarantine and isolation. But they've kept me in really good spirits."
"I am doing so much better. Cassie's family, I have to thank for that because they literally nursed me back to health and I don't know what I would do if it wasn't for them, so I am doing so much better," Underwood added.