An efficient one-pot synthesis of branched poly(3-alkylthiophene)s (b-P3ATs) is achieved via a dehydrohalogenative polycondensation reaction. The structures of the b-P3ATs are assigned based on ¹H NMR spectra by comparing them to a model dendritic polymer and oligo(3-hexylthiophene-2,4-diyl). The palladium-catalyzed dehydrohalogenative polycondensation of 2-bromo-3-alkylthiophenes was found to provide P3AT with tunable degree of branching (DB = 0–0.42) and high molecular weights. Viscosity measurements of the different b-P3ATs indicate that they display a more globular morphology compared to regiorandom P3AT and regioregular P3AT in solution, thereby confirming the branched structure.