Like countless showbiz couples before them, they've blamed the break-up on the 'pressures of work'.
Kylie was with model James for two-and-a-half years. Just a few months ago Kylie said she was "sure" she would end up marrying James and settling down.
A statement from Kylie said they "still love each other" and the split is completely friendly.
"This has been a very difficult and emotional decision to make, but we feel
that it is appropriate at this time."
Kylie is currently wowing crowds on her hugely successful UK tour.