Novel X-shaped conjugated oligothiophenes, which form a family of well-defined C-4-substituted compounds with a core thiophene ring that bears four short-chain branches containing alpha-alpha and alpha-beta linkages, have been designed and synthesized by a facile synthetic route. Their optoelectronic properties can be electronically fine-tuned by manipulating the segments of the branches. In solution, the four compounds show strong photoluminescence with emission maxima located at 459, 491, 494, and 547 nm. The optical properties of their films suggest an interesting conjugated effect in these X-shaped oligomers. Cyclic-voltammetry measurements of these compounds have been performed, and corresponding stable polymers from two of the monomers have been prepared by electrochemical polymerization. UV-vis absorption and emission properties of the resultant electroactive polymers are studied, indicating that the optical properties of the 3D polymers could be controlled by repeated potential scans.