With NASA’s current plans to establish a long-term cislunar presence through the lunar space station, Gateway, there is a significant interest in exploring potential missions that either conclude at or originate from the Gateway. Gateway will be placed in an Earth–Moon L2 southern near-rectilinear halo orbit and will act as a staging outpost for Moon-based missions and beyond. Several proposed missions are centered around the Gateway, creating an opportunity for secondary payloads with smaller spacecraft, such as CubeSats, to use the Gateway as a starting point for cislunar or deep space missions. As such, this work performs a reachability analysis of a low-thrust CubeSat departing from the Gateway and explores mass-optimal transfers to families of Sun–Earth L2 orbits. The results of this research show that a low-thrust spacecraft producing approximately [Formula: see text] of acceleration can reach Sun–Earth L2 orbits from the Gateway with as little as [Formula: see text] of [Formula: see text]. This work presents trade studies to determine transfer costs from the Gateway as a function of the Sun angle at departure and the target orbit. As a reference mission scenario, trajectories to the James Webb Space Telescope are generated to explore transfer costs for an uncrewed servicing mission from Gateway.