A one-pot synthesis of ortho-arylated 9-(pyridin-2-yl)-9H-carbazoles via C-H bond activation, in which palladium(II)-catalyzed cross-coupling of 9-(pyridin-2-yl)-9H-carbazoles with potassium aryltrifluoroborates is presented. Silver nitrate and tert-butanol were proved to be the best oxidant and solvent for the process, respectively. The product yields fluctuated from modest to excellent, and the reaction showed sufficient functional group tolerance. p-Benzoquinone served as an important ligand for the transmetalation and reductive elimination steps in the catalytic process. The key intermediate of the reaction, 9-(pyridin-2-yl)-9H-carbazole palladacycle was isolated and confirmed by X-ray crystallography. The kinetic isotope effect (kH/kD) for the C-H bond activation step was measured as 0.87. In addition, Hammett experiment gave a negative rho value, -2.14 with a reasonable correlation (R2 = 0.90). The directing group, pyridyl was demonstrated as a removable functional group. Finally, a rational catalytic mechanism is presented based on all experimental evidence.