The aim was to report the use low-level laser therapy (LLLT) in the management of hypersensitivity in an adolescent with molar incisor hypomineralization (MIH) and the impact of LLLT on his oral health-related quality of life (OHRQoL). Clinical examination revealed severe MIH with hypersensitivity, in all first permanent molars and incisors. The treatment proposed was desensitization with fluoride and esthetic rehabilitation of the affected teeth. Then, LLLT was applied perpendicularly in a continuous mode (wavelength of 808 nm, power of 100 mW, dose of 1 J, and fluence of 35 J/cm2). The visual analogue scale was applied each session of LLLT. The child perceptions questionnaire (CPQ11–14) was administered at the beginning and the end of the treatment. It was concluded that LLLT can be indicated in the management of hypersensitivity in an adolescent with severe MIH to control pain and to improve his OHRQoL.