Is this for indoors or outdoors?
Outdoors it is absolutely undebatably totally fine (although kind of expensive
).
Indoors it is maybe questionable and probably better avoided (but
not "OMG, get it out of there!"), for two reasons actually.
First, because cedar fumes are theoretically bad for the respiratory system. That is, they are definitely bad *in a lab setting*, but it is not clear that they harm chickens very often IN THE REAL WORLD. Plenty of people have used cedar shavings for years and years and years without problem, and in fact commercial broiler barns frequently use them as bedding (and before you get all 'oh well they mistreat their chickens', remember that anything that causes ANY extra mortality tends to get frowned on b/c they are operating on such a wafer-thin profit margin; although it is also true their chickens are only there for 4-6 wks so not getting longterm exposure). Since lots of people use it with no detectible problems and it is rare to hear of anyone *with* an identifiable problem from cedar shavings (and that tends to be people with day-old chicks in poorly ventilated brooders full o' cedar), personally I do not see it as being this big huge OMG scary risk that a lot of people on this forum like to think. Still, since we know that the volatile oils that come off cedar are NOT good for you, if you can avoid it, probably better to, especially if there is any question about how freely-ventilated your coop is.
And second, because *mulch* generally makes lousy bedding/floor-litter. It is not absorbant at all, does not compost well, is hard to spot-clean compared to shavings or chopped straw, and egregiously expensive. Mulch is fine in the run (with some caveats -- see my 'fix a muddy run' page, link in .sig below) but just does not really do a good job with the functions you want as *indoor* litter.
If it were me, I would either haul it out now before it gets too mucky and use it on my garden beds instead; or at least when it comes time to clean it out I'd switch to something else.
JMHO, good luck, have fun,
Pat