[en] Recently, two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have attracted much attention due to their promising applications in the fields of electronics and optoelectronics. Controllable growth of TMDC heterostructures stimulates new interest by tuning their optical and electronic properties. Herein, large-scale lateral MoSe₂–MoS₂ and MoSe_2(1−x)S_2x–MoS₂ heterostructures have been synthesized through one-step epitaxial ambient-pressure chemical vapor deposition method and we found that the growth time plays an important role in the formation of lateral heterostructures. Lateral MoSe₂–MoS₂ heterostructures have been systematically characterized by using atomic force microscopy, Raman spectroscopy and photoluminescence spectroscopy. Corresponding surface potential and charge distributions of MoSe₂–MoS₂ heterostructures have been investigated by employing Kelvin probe force microscopy. We found that the electrostatic properties of MoSe₂–MoS₂ heterostructures can be effectively tuned by injecting charges through conductive atomic force microscopy. Our results pave a new route for constructing 2D lateral heterostructures toward electronic and optoelectronic applications. (paper)