We report the carrier density dependence of the magnetotransport property in the correlated Dirac semimetal CaIrO₃. In the dilute carrier density region (n_(rm H) ∼ 2.2 × 10¹⁶ rmcm⁻³) at 2 K, the mobility exceeds 1.0 × 10⁵ rmcm²/rmVs at 2 K, and the transverse magnetoresistance (MR) reaches 2,000 % at 12 T. The analysis of quantum oscillations and Hall conductivity shows that the Fermi velocity is nearly independent of the cross-sectional area of the Fermi surface, or equivalently the carrier density, supporting a k-linear dispersion of the Dirac node. The field dependence of magnetoresistivity is nearly B-linear in the moderate carrier density region (nH ≥ 4 × 10¹⁶ cm⁻³), but scales with B^α (α > 2) in the lower carrier density region. The variation of magnetoresistivity is likely affected by the enhanced long-range Coulomb interaction in the quantum limit, where Dirac electrons are subject to the magnetic confinement.