"I had stuff on with my kids, she made us all wait for three hours or something, and then lobs up and has attitude," he said.
"If I'm making everyone wait, which happens … at least charm it on a bit. Go, 'Oh I'm so sorry I'm late.' Make up something. Iggy would walk in and go, 'My time is my time, whatever, get over it.'"
Sebastian recently told Stellar that he "hated" his time on The X Factor, saying, "It was just childish, with all the bickering".
"You had guest judges who weren't invested — and the audiences aren't stupid, they can see that.
"Iggy wouldn't rock up. And when she did, she'd just roll her eyes. I hated it. I really struggled that year."
Not long after he made those comments Azalea posted a not-so-cryptic tweet that read: "I don't actually give a f**k about other people's opinions; I just can't turn down the chance to tell someone they're a dumb b**ch. It's in my blood & there is no cure!"
Sebastian wasn't the only one who didn't love working with Azalea on The X Factor. In 2016 fellow judge Adam Lambert told the 2Day FM breakfast show that the diva rapper was "a complicated girl".
"She doesn't really know anything about singing," he said.
"I mean let's face it, no one's rapping on the show at this point, so it's like 'uhhhh what is she going to say?'
"I think she's embarrassed that she doesn't know anything about singing — so maybe she's just defensive … and Guy (Sebastian) and I are giving all this technical talk, so maybe she just feels threatened."
Sebastian is back on TV this weekend as a coach on the new series of The Voice alongside Boy George, Kelly Rowland and Delta Goodrem.
"I'm loving the chemistry between the coaches, we actually like each other," he told Kyle and Jackie O this morning.