A level shifter that supports wide voltage range operation by adaptively boosting local supply voltage to its input stage. The level shifter may interface an input (low) voltage domain and an output (high) voltage domain. In the level shifter, an input stage may receive an input signal from the input voltage domain, and an output stage may generate an output signal to be sent to the output voltage domain. In the level shifter, the power supply to the low-voltage input stage is automatically and adaptively boosted to effectuate level conversion of the input signal. A boost control signal is generated when the output signal fails to switch or is slow to switch in response to a corresponding switching of the input signal. In this manner, the voltage operating range of the level shifter is increased. Because boosting is engaged only when needed, the level shifter provides efficient operation with self-adaptability.