A smart flexible porous bilayer combining a polydimethylsiloxane (PDMS) upper layer with a hydrogel lower layer is introduced for efficient all-day dynamic passive cooling. The PDMS layer, with high solar reflectivity (0.930) and emissivity (0.952), provides excellent radiative cooling and protects the hydrogel from solar exposure. The hydrogel layer enables dynamic evaporative cooling through water evaporation and absorption. The synergy of the two layers significantly enhances cooling performance, achieving peak cooling powers of 424.4 and 650.6 W m⁻² during sunny and cloudy mid-days, respectively. The bilayer also performs better than PDMS alone during cold nights, maintaining a temperature 3.2°C higher than PDMS, while showing comparable performance during hot nights. The bilayer maintains good cooling performance even under continuous cloudy conditions, demonstrating its potential for efficient all-day passive cooling. The PDMS layer's hierarchical pores enhance solar reflectivity and emissivity, while the hydrogel layer provides moisture absorption and evaporation. The bilayer's design enables dynamic passive cooling throughout the day, adapting to varying environmental conditions. The study highlights the effectiveness of combining radiative and evaporative cooling for improved cooling performance and energy efficiency.A smart flexible porous bilayer combining a polydimethylsiloxane (PDMS) upper layer with a hydrogel lower layer is introduced for efficient all-day dynamic passive cooling. The PDMS layer, with high solar reflectivity (0.930) and emissivity (0.952), provides excellent radiative cooling and protects the hydrogel from solar exposure. The hydrogel layer enables dynamic evaporative cooling through water evaporation and absorption. The synergy of the two layers significantly enhances cooling performance, achieving peak cooling powers of 424.4 and 650.6 W m⁻² during sunny and cloudy mid-days, respectively. The bilayer also performs better than PDMS alone during cold nights, maintaining a temperature 3.2°C higher than PDMS, while showing comparable performance during hot nights. The bilayer maintains good cooling performance even under continuous cloudy conditions, demonstrating its potential for efficient all-day passive cooling. The PDMS layer's hierarchical pores enhance solar reflectivity and emissivity, while the hydrogel layer provides moisture absorption and evaporation. The bilayer's design enables dynamic passive cooling throughout the day, adapting to varying environmental conditions. The study highlights the effectiveness of combining radiative and evaporative cooling for improved cooling performance and energy efficiency.