Osbourne, 69, hasn't shied away from her support for The Pirates of the Caribbean actor throughout the trial between the former spouses. She previously described him as a "gentle soul" after he won his defamation case against Heard.
But on Monday's (6 June) segment of the Lorraine show, Osbourne didn't pick a side - she decided to call out both of the actors.
"'Now the court case is behind him, it must be difficult for you as a friend watching that and seeing him going through that," said presenter Lorraine Kelly.
The former X Factor judge replied: "It's very ugly, for both of them. Listen, what goes on at home between two people, nobody knows all the ugly details - and we all have our ugliness in every relationship but theirs was extreme."
Depp sued the Aquaman actress for $50m following a 2018 Washington Post op-ed she wrote that claimed she was a victim of domestic abuse. She didn't name the actor in her story.
Heard countersued him for $100m and claimed that Johnny's lawyer Adam Waldman defamed her by calling her claims a "hoax."
Osbourne hit out at the couple's relationshipGetty images
As the case came to a close on Wednesday (1 June), Depp won the trial and was awarded more than $10m, which vindicated his stance that Heard falsified claims that she was abused by him before and during their brief marriage.
In conversation with TalkTV's Pies Morgan Uncensored, Osbourne admitted that she didn't anticipate Depp winning the case despite her support for him.
"Wow, it wasn't what I was expecting. I mean, I wanted Johnny to win, but I didn't expect him to."
She added: "[Johnny] is a gentle soul. I can tell you last night, he spent about 45 minutes in his dressing room on his knees, talking to this little girl that was reading her diary to him."
Despite this, Osbourne noted that Depp and Heard's union was "toxic".
They were both abusive, both very, very abusive to each other," she said before adding that Heard "could have left" at any point and wasn't "some innocent little wallflower."
Osbourne further added that Heard "wanted to destroy" Johnny.
"She could have backed out somehow; she could have got to him, there could have been something to save it going on."
Following the defamation trial, Depp has hopes to revive his career, and Osbourne believes it could be possible for him to bounce back because he has a "huge worldwide audience."