Diabolical Fullmoon Mysticism is the debut studio album by Norwegian black metal band Immortal.

It was released on 1 July 1992 through Osmose Productions.

It is the only album to feature Armagedda on drums.

The album was issued as a standard CD, a limited edition LP, a limited edition picture disc and a limited edition cassette tape.

John Serba of AllMusic said, "Diabolical Fullmoon Mysticism presents the germ of a soon-to-be-great black metal outfit", calling it "as rancid and unholy as other early Norse efforts, albeit a hair more melodic and listenable than some of its peers", though "one's time is much better spent with subsequent albums.