MXenes are a prominent family of two-dimensional (2D) materials due to their metallic conductivity and abundant surface functionalities. Although MXenes have been extensively studied as bulk particles or thick films, thin and transparent films are needed for optical, optoelectronic, sensing and other applications. In this study, we demonstrate a facile method to fabricate ultrathin (~10 nm), TiCT MXene films by an interfacial assembly technique. The self-assembling behavior of MXene flakes resulted in films with a high stacking order and strong plane-to-plane adherence, where optimal films of 10 nm thickness displayed a low sheet resistance of 310 Ω/. By using surface tension, films were transferred onto various types of planar and curved substrates. Moreover, multiple films were consecutively transferred onto substrates from a single batch solution, showing the efficient use of material. When the films were utilized as gas sensing channels, a high signal-to-noise ratio, up to 320, was observed where the gas response of films assembled from small MXene flakes was ten times larger than that from large flakes. This work provides a facile and efficient method to allow MXenes to be further exploited for thin film applications.