A chelation-assisted oxidative addition of gold(I) into the C–C bond of biphenylene is reported here. The presence of a coordinating group (pyridine, phosphine) in the biphenylene unit enabled the use of readily available gold(I) halide precursors providing a new, straightforward entry towards cyclometalated (N^C^C)- and (P^C)-gold(III) complexes. Our study, combining spectroscopic and crystallographic data with DFT calculations, showcases the importance of neighboring, weakly coordinating groups towards the successful activation of strained C–C bonds by gold.