The pop princess met the British actor on the set of his US series ‘Galavant’ in 2015, when she made a guest appearance.
The couple announced their engagement in February last year.
According to The Sun, the 48-year-old singer has thrown Joshua out of her West London home, after he reportedly ‘grew close’ to a Spanish actress.
A source told the newspaper: “She no longer trusts him.”
The news comes just days after Kylie was pictured for the first time without her engagement ring.
The star shared a snap of her in a recording studio on Instagram, obscuring her ring finger by drawing hearts across the picture.
But songwriter Grace Barker, who is working on Kylie’s forthcoming album, also shared a snap, which showed her without the huge art deco sparkler.
The Sun’s source revealed: “She is absolutely devastated, totally heartbroken.”
Just last month Kylie confirmed she would be taking Joshua’s surname when they eventually tied the knot.
Meanwhile, Kylie has thrown herself back into work, announcing she has signed a new record deal with BMG.
The star promised fans she would put her “heart and soul” into her forthcoming album, which is set to be a “classic Kylie pop album”.
She shared the news of her new label on Instagram, sharing a photo of her at BMG’s London HQ.
“#Lovers So happy to announce my new record label is BMG. I promise you will have my heart and soul in this next record.”