The silicon carbide (SiC) 3C polytype microparticles with p-type conductivity are investigated by X-band electron paramagnetic resonance (EPR) technique in a wide temperature interval. Morphological and Raman studies show that the mean particle diameter is ≈8 μm, and the SiC polytype is purely 3C. At T = 10 K, the EPR spectrum of the shallow boron acceptor substituting cubic site (B_K), with C_3V symmetry and anisotropic g- and A-tensors resulting from static Jahn–Teller effect, is observed. At T > 30 K, a continuous transition from static to dynamic Jahn–Teller effect for B_K is detected. The temperature-dependent B_K principal g-values are explained by the transitions between the ground and excited vibronic states of B_K. At T = 130–150 K, the B_K center is characterized by T_d symmetry and isotropic g- and A-tensors. At T = 60–190 K, an additional single EPR Lorentzian line with short spin relaxation times and isotropic g-value close to B_K average g-value is observed. It was explained by averaging the anisotropic spectrum caused by rapid transitions between the boron ground and excited vibronic states split by Jahn–Teller potential. In addition, the EPR signal from carbon vacancy with characteristic superhyperfine structure is observed at T = 10–298 K.