Yes it is. It's called krausening.
You have to really, really understand your fermentation processes though. You have to bottle it at just the right gravity for the style. If you bottle it too soon, you'll overcarbonate and create bottle bombs. If you bottle it too late, you'll be undercarbonated or flat.
Another option is to reserve just the right amount of your wort before fermentation begins. Just put the correct amount in a sanitized canning jar and keep it refrigerated. When your beer is fully fermented out and ready for bottling, you can add the canned wort to the fermented beer and bottle it.