As pointed out by Anon, bioluminescence is biologically expensive....unless you're not the one paying the bill. There are many other ways to gain bioluminescence (or an equivalent effect, as seen in Point 2).
The blue glaucus preys on poisonous siphonophores like the Portuguese Man-of-War and stores nematocysts from its prey in its own tissue as a defense. Likewise, Costasiella kuroshimae, also known as the "leaf sheep" or the "leaf slug," eats algae and retains the algae's chloroplasts for extra energy. Finally, poison dart frogs get their poison from their insect prey, which we know because dart frogs in captivity don't exhibit the toxicity of their wilder brethren.
In much the same way, your creatures could gain bioluminescence by taking bioluminescent chemicals or cells from the plants and/or animals they eat.
2. Chemical Absorption
Similar to 1, but not quite. Ever heard of the scaly-foot snail? Yeah, well, the outer layer of its shell is made of iron sulfides, specifically greigite and pyrite. Even more interestingly, the inner layer of its shell is made of aragonite, a fluorescent form of calcium carbonate. Aragonite is also found in the shell of various mollusks and corals, being formed by physical or biological processes.
Scorpions, platypi, and various other animals also exhibit fluorescence when exposed to UV light. In fact, fluorescent animals are actually quite common, as some curious researchers with a UV torch found. It doesn't exist in mammals, but fish, amphibians, certain arthropods, and many other species do exhibit biofluorescence.
This tells us that if nothing else, it'd be an evolutionary cinch to have most, if not all, of your alien lifeforms fluorescent (since your planet is similar to Earth). Now, this is not bioluminescence, but it's pretty dang close.
It's also more plausible, since if animals are regularly exposed to or ingest fluorescent materials, there must be an awful lot of fluorescence in the environment, they'll likely become fluorescent to better blend in. There is another reason; according to livescience.com, "Experiments with tardigrades in the Paramacrobiotus genus revealed that fluorescence protects them like a layer of sunscreen, transforming damaging UV rays into harmless blue light, according to a new study." (For more on that, click here.)
In other words, biofluorescence can protect living organisms from UV, so if the ozone layer is gone or depleted, you better believe there will be a lot of biofluorescence, and a lot of glowing to come with it. If you decide to make your planet a future Earth, with clouds of pollution and depleted ozone, that would create A) a dark environment and B) give natural selection a reason to make the world glow.
Anyway, I hope this helps!