In the One Piece world, bounty hunters collect their rewards by capturing or defeating wanted criminals and turning them in to the World Government.
After capturing a bounty target, the bounty hunter brings the criminal, or proof of their capture, to a nearby Marine base or directly to Marine officers. The Marines then verify the identity of the criminal and the bounty amount.
Once confirmed, the bounty hunter receives their reward, which is typically paid in Berries, the currency used in the One Piece universe. This process allows bounty hunters to profit from capturing dangerous pirates and criminals, contributing to the overall safety and stability of the world.