Natural pollen, one of the most fascinating biological materials in existence, exhibits chemical modifications and tunable optical property in the process of fossilization. Herein, we firstly fabricated nature-based fossil-like pollen grains (F-PGs) with UV-responsive optical properties through a facile concentrated H2SO4 treatment. The F-PGs featured incomplete carbonization property while remaining the UV-active alkyl aliphatic groups, which could initiate the carbonylation of F-PGs surface under UV irradiation, thus endowing the distinct UV dose-dependent photochromic and fluorogenic dual-function of F-PGs. With the sustainable, easy-preparation and cost-effective advantages, the F-PGs were used to construct dual-functional films. The F-PG films presented high photochromic contrast (ΔE* = 32) to serve as smartphone-readable quick response code-patterned UV sensors, which indicated the highest reported cumulative dose of UV irradiation (108 J cm−2, equivalent to 10 days of exposure to sunlight). In addition, the UV-irradiated F-PG films with the fluorogenic property also showed wide applications in one-step and flexible photo-reduction of various metal ions to nanoparticles. Collectively, the novel fossil-like pollen grains and functional films pave the way for utilization of natural pollen for UV-responsive applications and provide a new insight for transporting the renewable biomass into photochromic and fluorogenic materials in the future.