A tissue closure device includes a clip including arms extending from proximal ends connected to one another to distal ends. The clip is biased toward an open configuration in which the distal ends extend away from a longitudinal axis of the clip. The arms are held in a closed configuration in which the arms are moved toward the longitudinal axis via an interior surface of a working channel through which the clip is passed until the clip is moved distally past a distal end of the working channel and permitted to revert to the biased open configuration so that the distal ends are positioned about a portion of tissue surrounding a tissue opening to be closed. The device also includes a locking element movable over the arms to lock the clip in the closed configuration in which the arms are drawn toward one another to grip tissue therebetween.