Construction of polycyclic heteroaromatics <i>via</i> metal-catalysed intramolecular X–CH activation

π-Conjugated heteroaromatic systems are known for their unique optical and electronic properties and are important for a wide range of semiconducting applications. Metal-catalysed C-H activation has emerged as a key strategy for developing a facile and economic route for the synthesis of a variety of novel π-conjugated heteroaromatics, which otherwise involves multistep synthesis through conventional methods. In this review, we summarise the synthesis, properties and applications of several heteroaromatics, such as <i>N</i>-heteroheptacenes, benzo[<i>de</i>]thioacenes, π-extended thienoacenes, metallocene siloles, spirosilabifluorene, benzo[<i>b</i>]silole-fused 9,9'-spirobi[fluorene], sila[6]helicenes, tetragermatetrathia[8]circulene, trisilasumanene, trigermasumanene, and tetrasilatetrathia[8]circulenes, which have been developed using the X-CH activation strategy.