Yes—red LEDs can work as darkroom safelights, and some darkrooms successfully use red LED strips powered from 12V supplies. However, don’t assume every red LED is automatically safe.

The key issue is spectral output: some LEDs are not as “pure red” as expected, especially if they use phosphors or are driven in ways that change their emission. In particular, any blue leakage would be a problem for darkroom paper.

So the practical answer is: use them only after testing. A simple safelight test is to leave a sheet of your paper exposed to the safelight for an extended time, then process it and check for fogging compared with an unexposed control sheet. If there’s no visible fogging under your normal working conditions, the light is likely suitable.

In short: red LEDs can be a cheap and effective safelight, but verify the exact LED you plan to use rather than relying on its color alone.