The Dual-Sliding Fin Lock Assembly provides a simple, cost-effective and secure locking mechanism that engages on the initial opening stroke of a fin of a flying object, using a minimal number of parts that are easy to manufacture. Two sliding locks, each having a protruding step, engage with two fin lugs each of which has a corresponding notch. When a step and a notch fit together, they form a contact plane which may be straight horizontal or inclined to ensure robust locking operation without the need for extremely tight tolerances on the individual parts or on the assembly. Since the sliding locks do not rotate around the pin that holds the fin lugs, they engage the fin lugs to arrest the rotation of the fin and retain it securely in the deployed position for the duration of the object's flight, guiding the object more accurately toward its destination.