Dual-tub junction-isolated voltage clamp devices and methods of forming the same are provided herein. The voltage clamp device can provide junction-isolated protection to low voltage circuitry connected between first and second high voltage interface pins. In certain implementations, a voltage clamp device includes a PNPN protection structure disposed in a p-well, a PN diode protection structure disposed in an n-well positioned adjacent the p-well, a p-type tub surrounding the p-well and the n-well, and an n-type tub surrounding the p-type tub. The p-type tub and the n-type tub provide junction isolation, the p-type tub can be electrically floating, and the n-type tub can be electrically connected to the second pin. The first and second pins can operate at a voltage difference below the junction isolation breakdown, and the second pin can operate with higher voltage than the first pin.