The rise of two-dimensional (2D) graphene-cognated crystals with nonzero band gaps like transition metal dichalcogenides has led to a rapidly increasing interest in their dimensionality-dependent anisotropic properties, which bear high potential for ultrathin electronics. 2D crystals of the III-VI metal chalcogenide InSe represent a new kind of material class predestined for the use in optoelectronic applications as highly responsive photodetectors and field-effect transistors. We present a solution-processable method for 2D ultrathin InSe nanosheets (≤5 nm with ligands, lateral sizes up to ∼800 μm) with a detailed characterization of the sheet formation by a lamellar ligand templated growth. Optical and electrical transport properties, as well as in depth analysis of the crystal structure and stoichiometry of the colloidal nanosheets by electron and atomic force microscopy, X-ray photoelectron spectroscopy, and scattering methods complete this comprehensive study on a wet-chemical alternative to produce ultrathin InSe nanosheets.