MXenes are two-dimensional (2D) transition metal carbides or nitrides that have recently gained interest with applications geared towards energy storage, catalysis, sensors, electronic devices, and medicine. While the currently used wet chemical approach allows large-scale MXene synthesis, bottom-up synthesis methods would widen the range of MXene structures available and open the road to new applications. Here, using in situ aberration-corrected scanning transmission electron microscopy, we demonstrate the homoepitaxial growth of an additional hexagonal TiC layer on surfaces of monolayer Ti3C2 (MXene), thereby forming new 2D materials Ti4C3, Ti5C4, and Ti6C5 at temperatures above 500 °C. Using density functional theory and force-bias Monte Carlo/molecular dynamics simulations, the growth mechanism of a single TiC ad-layer and the energies governing migration and diffusion are elucidated. These findings provide insights on 2D materials growth and pave the way to fabricate MXenes with controlled morphology for tailored functionality.