  We report an experiment that uses the environmental selection, a key concept
in the recent theory of quantum Darwinism, as a mechanism to realize the
entanglement filter, a useful quantum information device that filters out
certain entangled states. In the experiment, the environment of two qubits is
controlled to favor an entangled state and kill other competing components in
the input state. The initial state has vanishing entanglement, but the state
surviving after interaction with the environment is close to a maximally
entangled state, with an entanglement fidelity of $(94.7\pm 1.9)%$ measured
through the quantum state tomography. We experimentally demonstrate that the
generated entanglement is robust under change of the initial state
configurations and the environmental parameters.
