During Wednesday night's episode of "Drop the Mic," the ladies, who were both wearing similar hot pink jumpsuits, trashed each other's careers, relationships and rapping ability. And both Simpson and Milian held nothing back.
For Milian's disses, she poked fun at Simpson's music, her acting chops, her current reality show she has with her husband, Evan Ross as well as her sister Jessica's series she had with her then-husband, Nick Lachey.
"Ash's smarter than Jess but still dumber than Homer," Milian rapped. "Your song 'Pieces Of Me' used to be the rage. But tonight I'm leaving pieces of you on the stage."
"Are you a worse singer or actor? It's hard to tell. You were on '7th Heaven,' but your acting was hell," she said. "Now you have a reality show with your hubby. You should have asked your sister how that worked out, dummy."
The "Dip It Low" singer, who actually dipped it low at one point, threw shade at the way Simpson spells her first name. "Can't sing, can't dance, and now you can't rap," she spit. "And by the way, who the hell spells Ashlee like that?"
But Simpson didn't take Milian's jabs lightly and fired back with some perfect comebacks of her own. "Who cares that you think I spell my name wrong. I'm the only one here who's had a hit song," the E! reality star said.
The mother of two shaded Milian's love life, including her failed relationship with Nick Cannon, who went on to marry Mariah Carey after they broke up.
"Nick Cannon dumped you, it hurts 'til this day," Simpson rapped. "I guess you could say, he just got Carey-d away."
"Your love life is rocky, I guess you deserve it," she added at another point. "Your love don't cost a thing -- and everyone still returns it."
Simpson also referenced the location of their battle -- Universal Orlando Resort in Florida -- and further slammed Milian. "You got destroyed, I'm too much to handle. But hey – at least you got a free trip to Orlando."
Both ladies absolutely killed it, but there could only be one winner. See who won in the clip above.