This paper reports a significant-loophole-free test of Bell's theorem using entangled photons. The experiment, conducted by a team of researchers from various institutions, aimed to simultaneously close the most significant loopholes in previous Bell test experiments. The setup involved a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors. The results showed a violation of a Bell inequality with high statistical significance, indicating that the probability of the observed outcomes occurring under local realism is less than \(3.74 \times 10^{-31}\), corresponding to an 11.5 standard deviation effect. The experiment closed the locality loophole by ensuring space-like separation between setting choices and measurements, the freedom-of-choice loophole by using space-like separated random number generators, and the fair-sampling loophole by achieving high system heralding efficiencies. Additionally, the coincidence-time loophole was addressed by using locally defined time slots. The experiment provides strong support for the idea that nature cannot be described within the framework of local realism.This paper reports a significant-loophole-free test of Bell's theorem using entangled photons. The experiment, conducted by a team of researchers from various institutions, aimed to simultaneously close the most significant loopholes in previous Bell test experiments. The setup involved a well-optimized source of entangled photons, rapid setting generation, and highly efficient superconducting detectors. The results showed a violation of a Bell inequality with high statistical significance, indicating that the probability of the observed outcomes occurring under local realism is less than \(3.74 \times 10^{-31}\), corresponding to an 11.5 standard deviation effect. The experiment closed the locality loophole by ensuring space-like separation between setting choices and measurements, the freedom-of-choice loophole by using space-like separated random number generators, and the fair-sampling loophole by achieving high system heralding efficiencies. Additionally, the coincidence-time loophole was addressed by using locally defined time slots. The experiment provides strong support for the idea that nature cannot be described within the framework of local realism.