The never-before-heard audio -- obtained by Daily Mail -- Welteroth is heard comforting a bawling Osbourne and telling her, "I know you're not racist" in a dressing room following her heated exchange with Underwood.
Welteroth also makes it a point to tell Osbourne she's been "set up" and claimed that showrunners wanted her to deliver the question that sparked the explosive on-air debate.
As Radar reported, Osbourne and Underwood were at each other's throats on the March 10 show after Sharon stood up for her friend Piers Morgan.
Piers was at the center of controversy after he made it clear that he didn't believe Meghan Markle's accusations that someone in the palace was racist, and most troubling, that he doubted what she said about being suicidal.
Underwood scolded Osbourne on live TV, saying she was giving "validation'" to Piers' "racist" views.
Following the blowup with Underwood, Welteroth allegedly drew even more attention to the topic when she reportedly complained about working in "a racially insensitive and hostile environment."
Osbourne exited the long-running talk show weeks later following an internal investigation.
Interestingly enough, Welteroth seemed to sing a different tune in the never-before-heard audio, which was caught on the co-host's mic after filming.
She appeared to have Osbourne's back immediately after the feud, revealing that she told producers "no" when they asked her to bring Piers' name up in the conversation.
"I said to them, this is going to be a train wreck," Welteroth is heard saying. "Sharon, I'm just so sorry that that went the way that it went."
Osbourne, who was sobbing, replied, "Do you know what it is though, when you have to sit there and defend yourself? It makes you look guilty because you can't get out of it.
"It's like calling somebody a pedophile, you can't deny it. What do you say?"
Welteroth also told Osbourne, "Sheryl loves you and respects you so much and had your back behind the scenes. She was not trying to attack you."
Reiterating that Underwood loves Osbourne, Welteroth continued, "And I know you're upset. I know it was terrible, but I just hope that once this blows over that you know Sheryl is your friend. She really is your friend.
"She doesn't think you're racist. I don't think you're racist. No one who knows you would ever say that or think that."
The audio is very telling, revealing how emotional Osbourne got over the whole ordeal which was sparked when Underwood asked, "What would you say to people who may feel that, while you're standing by your friend, it appears that you gave validation or safe haven to something that he has uttered that is racist, even if you don't agree?"
Osbourne would later claim she was "blindsided" by the question. Underwood has claimed she has PTSD from the feud.