Michael Szewczuk, 19, admitted two counts of encouraging terrorism and five charges of possessing terrorist documents before his arrest last December.
The charges relate to publishing messages on social network Gab and having documents with titles including The Anarchist Cookbook and White Resistance Manual.
The Daily Telegraph reported Szewczuk used an online pseudonym and posted online calling for the ‘systematic slaughter’ of women.
The defendant appeared in the dock of the Old Bailey alongside 18-year-old Oskar Dunn-Koczorowski, from west London, who admitted two charges of encouraging terrorism in December.
They related to the neo-Nazi group Sonnenkrieg Division which used the social media platform Gab to post extreme racist images.
The Telegraph reported one picture showed Prince Harry set against a swastika with a gun pointed at this head, along with the comment: 'See ya later, race traitor!'
Judge Rebecca Poulet QC granted the pair continued conditional bail ahead of their sentencing on June 17.
She ordered a pre-sentence report be prepared for Szewczuk, from Bramley in Leeds, but warned it should not be seen as a sign he would not receive a prison term.