Laser-based material processing systems, exhaust systems, and methods for using such systems are disclosed herein. One embodiment of a laser-based material processing system can include an exhaust assembly configured to remove contaminants from a material processing area. The exhaust assembly can include a vacuum source and an exhaust plenum carried by a moveable arm of a gantry-style laser beam positioning assembly. The moveable arm can extend along a first axis and can be moveable along a second axis generally normal to the first axis. The exhaust plenum can extend lengthwise in a direction generally parallel with the first axis. The exhaust assembly can also include an intake slot extending lengthwise along the exhaust plenum across at least a portion of the material processing area. The exhaust assembly can further include one or more flexible exhaust ducts in fluid communication with the vacuum source and the exhaust plenum.