The magnetic ground state of single-crystal RuO₂ has been investigated using muon spin rotation/relaxation (μSR) experiments. The study reveals that there is no spontaneous muon spin precession signal due to a magnetic field, which is expected in a magnetically ordered phase, in the temperature range of 5–400 K. First-principles calculations suggest that the magnetic moment of Ru is much smaller than previously reported, indicating that the bulk crystal is likely nonmagnetic. The μSR results, combined with density functional theory (DFT) calculations, rule out the possibility that muons are localized at sites where the internal magnetic field cancels out. These findings strongly suggest that the antiferromagnetic (AFM) order previously reported in RuO₂ does not exist in the bulk crystal. The study also shows that the μSR time spectra exhibit only monotonous relaxation without sinusoidal oscillation, indicating no homogeneous internal magnetic field at the muon sites. The upper limit for the Ru magnetic moment size is estimated to be 4.8(2) × 10⁻⁴ μB, which is significantly smaller than the previously reported value of 0.05 μB. These results provide experimental evidence that the electronic ground state of RuO₂ is a nonmagnetic metal. The study concludes that there is no bulk AFM order in RuO₂, contradicting earlier reports. The μSR technique, which is highly sensitive to local magnetic fields, was used to investigate the magnetic properties of RuO₂, and the results support the nonmagnetic nature of the bulk crystal. The study also discusses the possibility of slow relaxation due to fast fluctuating magnetic order, but this is ruled out by the experimental results. The findings suggest that RuO₂ is a nonmagnetic metal with a unique electronic structure that is different from previously assumed.The magnetic ground state of single-crystal RuO₂ has been investigated using muon spin rotation/relaxation (μSR) experiments. The study reveals that there is no spontaneous muon spin precession signal due to a magnetic field, which is expected in a magnetically ordered phase, in the temperature range of 5–400 K. First-principles calculations suggest that the magnetic moment of Ru is much smaller than previously reported, indicating that the bulk crystal is likely nonmagnetic. The μSR results, combined with density functional theory (DFT) calculations, rule out the possibility that muons are localized at sites where the internal magnetic field cancels out. These findings strongly suggest that the antiferromagnetic (AFM) order previously reported in RuO₂ does not exist in the bulk crystal. The study also shows that the μSR time spectra exhibit only monotonous relaxation without sinusoidal oscillation, indicating no homogeneous internal magnetic field at the muon sites. The upper limit for the Ru magnetic moment size is estimated to be 4.8(2) × 10⁻⁴ μB, which is significantly smaller than the previously reported value of 0.05 μB. These results provide experimental evidence that the electronic ground state of RuO₂ is a nonmagnetic metal. The study concludes that there is no bulk AFM order in RuO₂, contradicting earlier reports. The μSR technique, which is highly sensitive to local magnetic fields, was used to investigate the magnetic properties of RuO₂, and the results support the nonmagnetic nature of the bulk crystal. The study also discusses the possibility of slow relaxation due to fast fluctuating magnetic order, but this is ruled out by the experimental results. The findings suggest that RuO₂ is a nonmagnetic metal with a unique electronic structure that is different from previously assumed.