π-Extended triphenylene frameworks, representing a privileged class of pericondensed polyarenes, serve as cornerstone structures in modern optoelectronic materials, bioactive molecule design, and supramolecular engineering. Their rigid C3-symmetric topology and delocalized π-surfaces enable unique charge transport characteristics and photonic responses distinct from lower-dimensional analogs like biphenyl or fluorene systems. While classical syntheses employing Friedel-Crafts trimerization or oxidative cyclodehydrogenation face challenges including step inefficiency, stoichiometric waste, and limited functional group tolerance, recent paradigm-shifting advances in transition-metal-catalyzed annulative cross-couplings have unlocked atom-economical routes to these fused polycycles. This review provides a comparative analysis of state-of-the-art catalytic strategies for triphenylene synthesis, with particular focus on palladium/nickel-mediated C-H activation protocols versus radical-based photoredox cascades. Mechanistic divergences between oxidative homocoupling of haloarenes and directing-group-assisted heterocoupling are examined through stereoelectronic arguments, addressing regiochemical control in π-extension processes. Substrate compatibility are critically mapped across metal catalysis, highlighting competing π- versus σ-activation pathways in fused-ring formation. Future directions propose the synergistic integration of machine learning-guided catalyst design, operando XAS/EPR spectroscopy, and electric-field-assisted assembly to transcend current synthetic limitations, ultimately enabling precision engineering of triphenylene-based quantum materials and bioresponsive nanosystems.