"My house burned down last night with my cat inside. R.I.P. My little Valentine," Von D wrote on her Twitter page alongside a photo of her pet early on Monday.
She also posted photo of herself standing next to what appeared to be charred remains of a room, saying: "In order to gain everything, you must lose everything."
Von D was in Canada at the time of the blaze, promoting her book, "The Tattoo Chronicles".
Von D and James, the CEO of custom motorcycle manufacturer West Coast Choppers, stepped out together in early September at the red carpet opening of her Wonderland gallery in Los Angeles. She told reporters she was in love with him. The status of their relationship is currently unclear.