Tobias Marcus Nuttall, 32, pleaded guilty in Stirling Gardens Magistrates Court on Wednesday over the stabbing death of Alisha Lauren Hendren-Krippner, 30, at a Perth home on August 20.
Ms Hendren-Krippner was transferred to Royal Perth Hospital in a critical condition with multiple injuries and died the same day.
Defence lawyer Simon Watters said that after negotiations with prosecutors, it was agreed that "criminal responsibility arises" for Nuttall.
Sporting a bushy beard, a cross on a chain around his neck and slicked-back shoulder-length hair, Nuttall appeared via video-link and showed no emotion when he entered his plea.
His case was adjourned to April 13 for mention ahead of his sentence in the WA Supreme Court, at a date to be fixed.
Nuttall was the co-host of a news review podcast called WakingWorld.
In an episode published about a month before Nuttall killed Ms Hendren-Krippner he and a British co-host named Dale discuss werewolves and the "deeper meanings behind Christian practice and what it means to embody or resist our wildest instincts".
After Nuttall's arrest, Dale reportedly told their listeners that his co-host would no longer be appearing on the show because had been charged with a serious offence but the episode appears to have been deleted.
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