A portable ultrasound system having a thumb controller is disclosed herein. A portable ultrasound system configured in accordance with one embodiment of the disclosure includes a transducer device and a hand-held base unit removably coupled to the transducer device. The base unit is configured to perform an ultrasound scan and to produce a split screen display. The split screen display includes an active image area at which images of a patient obtained from ultrasound signals received by the transducer device are displayed. The split screen display also includes a thumb control area that is accessible by a user's thumb when holding the portable ultrasound system. For example, the thumb control area can include a thumbwheel having one or more controls that can be selectively activated by the user's thumb when holding the portable ultrasound system and are rotatable on and off of the thumb control area.