Yes, it does contradict itself. But that doesn't make it any less useful as a philosophical position as many nihilists will tell you. Nihilism may be better understood as an aesthetic rather than a properly mature philosophical position (which explains its singular attraction to certain kitted out in black adolescents).
Consistency is not everything. After all the Liars Paradox contradicts itself yet Goedel was able to spin out a major innovation in mathematical practise in the 20th century, or as Nietzsche (portentously) put it - 'very well, I contradict myself'.
However all of the above is probably a banalisation of the nihilistic proposal; a modern exponent of this tendency is Ray Brassier. In Nihil Unbound: Enlightenment and Extinction he makes a mature and considered defence of this position. In this interview he says:
Very simply, nihilism is a crisis of meaning. This crisis is historically conditioned, because what we understand by ‘meaning’ is historically conditioned. We’ve moved from a situation in which the phenomenon of ‘meaning’ was self-evident to one in which it has become an enigma.
He marks the point where this begins to happen:
The emergence of modern mathematized natural science around the 16th Century marks the point at which this way of making sense of ourselves and our world begins to unravel. It does not collapse all at once, but it begins to lose its official theoretical sanction in the discourse of theology once the new science starts chipping away at the latter’s basic conceptual underpinnings. Over the course of a few centuries, the longstanding assumption that everything exists for a reason, that things are intrinsically purposeful and have been designed in accordance with a divine plan, is slowly but systematically dismantled, first in physics, then in chemistry, and eventually in biology, where it had held out longest.
But he concedes its a position that has been rehearsed before:
Of course, ‘nihilism’ in its broadest sense, understood as the predicament in which human life and existence more generally are condemned as ‘meaningless’ (i.e. ‘purposeless’), certainly predates the development of modern science (think of Ecclesiastes). But the emergence of modern science lends it a cognitive import it did not previously enjoy, because where pre-modern nihilism was a consequence of a failure of understanding – “We cannot understand God, therefore there is no meaning available to creatures of limited understanding such as we” – modern nihilism follows from its unprecedented success – “We understand nature better than we did, but this understanding no longer requires the postulate of an underlying meaning”. What has happened in this shift is that intelligibility has become detached from meaning
He moves distances himself from existentialists by moving further than they dared:
existentialists thought it was still possible for human consciousness to provide the meaning that was absent from nature: existence may be meaningless, but man’s task is to provide it with a meaning. My contention is that this solution is no longer credible, because a project is now underway to understand and explain human consciousness in terms that are compatible with the natural sciences, such that the meanings generated by consciousness can themselves be understood and explained as the products of purposeless but perfectly intelligible processes, which are at once neurobiological and sociohistorical.
However, in another interview he states However he isn't a positivist or a physicalist:
I would like to maintain a commitment to science’s ultimate epistemic authority while resisting the dogmatic temptation to enthrone the entities, mechanisms and structures postulated by contemporary science as ultimate realities.
He concedes that science cannot explain what is ultimate:
But the relationship between science and metaphysics is complicated: science says nothing about how to tell the difference between what is and what is not ultimately ‘real’.
Given his commitment to the objectification of human experience he has an:
antipathy to what Quentin Meillassoux calls ‘correlationism’—the doctrine, especially prevalent among ‘Continental’ philosophers, that humans and world cannot be conceived in isolation from one other.
Coming back to the ultimate, he does concede that the epistemic excavation of science is far from everything:
That’s why I endorse a ‘transcendental realism’ according to which science knows the real but the nature of this ‘real’ is not strictly speaking objectifiable. The basic idea is that we know the real through objects, but that the real itself is not an object.
Essentially he reaffirms man & reason; and through this the objectification of man through reason. Hence his slogan - "I am a nihilist because I believe in truth".
In passing I just want to note that the title of his book refers to the poem Prometheus Unbound by the atheistic Poet Shelley who affirms the centrality of Man to Man; & Of course Buddhism - the extinction of subjectivity & the enlightenment of our objectivity.
Personally I disagree with his thesis that subjectivity can be objectified and his antipathy to correlationism.