An interlocking cable cleat secures cables to a ladder rack. The interlocking cable cleat is formed from a first cable cleat half and a second cable cleat half. Each cable cleat half includes an outer surface, an inner surface, and at least one mounting hole extending from the outer surface to the inner surface. Semi-circular keys extend from the inner surface of each cable cleat half around the mounting holes in the cable cleat halves defining slots in the remainder of each mounting hole. Each slot receives one of the semi-circular keys from an opposing inverted cable cleat half to interlock the first cable cleat half to the second cable cleat half.