"Julianne is the reason I started doing ballroom!" Johnson shared. "So to have her judge this finale just means the world."
Cheryl Burke -- the pro partner of celeb Peloton instructor Cody Rigsby -- was equally thrilled, telling ET, "I've known Julianne since she was 10 years old so we go way back."
"It's always nice to have old contestants or old pros come back on our show and judge, so she is amazing and she knows what to look for," Burke shared. "She's a great replacement for Derek, so I'm really excited."
On Tuesday, just a day after he served as a judge on the ABC show's semifinals, Derek revealed that he had tested positive for a breakthrough case of the coronavirus.
"Even though I've been fully vaccinated, I've just been diagnosed with a breakthrough case of COVID," he revealed in a video posted to his Instagram. "I just found out and I feel OK. I feel strong. I'm currently taking advice from medical professionals to get better as fast as I can. I'm currently in quarantine."
Hough assured fans, "I'll make sure to keep you guys all updated with what's going on, but I just want to send my love out there to all. Stay safe."