Minimally invasive nonsurgical treatment (MINST) aims to remove an etiology with minimal damage to the healthy periodontium and provide the ideal healing environment. This case series introduces the novel protocol of laser-assisted MINST (LAMINST), combining minimally invasive surgery with a dental laser. A total of 25 patients (32 teeth) with advanced periodontal disease were enrolled and received periodontal treatment by following the LAMINST protocol. Probing depth (PD), recession, clinical attachment level (CAL), bleeding on probing (BOP), plaque presence, and site mobility were evaluated preoperatively and at 6 months. Based on the periodontal evaluations, all cases were diagnosed as stage III grade C periodontitis. Six months after LAMINST, the average PD reduction was 4.44 mm and CAL improved by 4.38 mm. Baseline mobility scores of 1 (6 teeth), 2 (9 teeth), and 3 (3 teeth) decreased to 1 (5 teeth) or 0 (13 teeth). The initial prognoses of 5 (hopeless; 15 teeth), 4 (questionable; 13 teeth), and 3 (poor; 4 teeth), improved to 4 (5 teeth), 3 (12 teeth), 2 (fair; 13 teeth), and 1 (good; 2 teeth). The number of BOP sites reduced from 179 to 12, and the number of plaque sites reduced from 173 to 9. All clinical parameters were improved after LAMINST. The application of LAMINST may overcome the traditional limitations of nonsurgical treatment, such as poor accessibility.