A diverse array of biologically active derivatives was derived by modifying the chemically active sites of dehydroabietylamine. Herein, we describe the synthesis of a new series of C-19-arylated dehydroabietylamine derivatives using a palladium-catalyzed C(sp3)-H activation reaction. Five analogues (3b, 3d, 3h, 3n, and 4a) exhibited antibacterial activity against Escherichia coli. Compound 4a exhibited strong inhibitory activity against DNA Topo II and Topo IV. Molecular docking modeling indicated that it can bind effectively to the target through interactions with amino acid residues. The synthesized compounds were tested in vitro for their antifungal activity against six common phytopathogenic fungi. The mechanism of action of compound 4c against Rhizoctorzia solani was investigated, revealing that it disrupts the morphology of the mycelium and enhances cell membrane permeability.