Are you describing a power filter? It depends. There is a great chance that it'll shred your Bettas lovely fins, though. In-tank Whisper filters work very well, and have a low setting that does not disturb the Betta. You have to understand that Bettas (besides Plakats) are more fin than they are body, a current will blow them around the tank constantly and really irritates them.

I totally recommend Small World filters, they connect to an air pump, and have sponge & carbon media that keeps the water looking clean. You will still need to do 100% changes every week on anything under 5 gallons, with or without a filter, as cycling is near impossible in a small tank.