An automotive safety harness for pets is disclosed, the harness including first and second closed loops formed by a length of webbing joined at opposite ends and secured at an intersection. The opposite ends at the second closed loop are permanently secured with the first closed loop at a position opposite the first closed loop from the intersection, a first fastener secured to an exterior surface at the position. A securing webbing is configured with first and second interface loops to slidably maintain the first and second closed loops at the position at one interface loop and receive the vehicle seat belt in the other, respectively. A second fastener is secured to the interior of the first interface loop surface, the first and second fasteners releasably engagable. A strap is connected to associate opposite sides of the second closed loop and includes a stretchable material portion for automatically refining fit of the second closed loop at the pet's torso without user intervention during and after harness mounting.