The objective of the study was to investigate cognitive-motor interference of walking while texting in people with multiple sclerosis (PwMS). The study included 30 PwMS, mean disease duration 11.8 (SD = 6.8) years, and 15 healthy controls. The investigation included a cognitive assessment; texting assessment based on 100 typed characters; and gait assessment under two different conditions: normal walking and walking while texting. Outcome measures included the Symbol Digit Modalities Test to assess cognition. Texting measures included accuracy (%) and duration(s). Gait was assessed with axial accelerometers to quantify temporal measures. The dual-task cost percentage for the walking tests and texting accuracy was determined by calculating the percentage change from a single task to a double task. The impact of texting while walking on gait measures was significantly higher in PwMS; furthermore, texting was less accurate compared to the healthy controls. The dual-task cost for texting accuracy in the PwMS group was 153.3 (SD = 105.7) compared to 8.9 (SD = 26.6) in the healthy group. A significant association was found solely in the PwMS group between cognition and texting accuracy while in a sitting position (R = 0.564) and while walking (R = 0.534). The dual-task cost of walking and texting appears to be unique in the MS population.