Yes, most pedal guitar tuners can be used in an effects loop in the same way as effects pedals.

You should ensure that the pedal is the first in the loop (before any effects), so that it receiving a clean signal from the guitar, and choose a pedal guitar tuner that has "true bypass" to ensure that it does not introduce any hum or other problems into your rig when not being used.

Pedal guitar tuners are the easiest to use on stage, especially for a quick tune-up between songs! Make sure you choose a tuner pedal that has a clear display that you can see from your standing position, in all lighting conditions. The Planet Waves pedal tuner is excellent in this respect.