BACKGROUND: The effect of interventions to the Sternocleidomastoid (SCM)-muscle, as an important element of neck movement which is overactive in individuals with chronic neck pain (CNP), are unknown. OBJECTIVE: The aim of the current study is to investigate the effects of SCM stretching and massage on pain, range of motion (ROM), endurance, disability, and kinesiophobia in individuals with CNP. METHODS: In this study, individuals with CNP were randomized 1:1 to parallel SCM-Group (n = 30) or control group (CG) (n = 30). Conventional physiotherapy was applied to CG. In addition to the same interventions applied to the CG, classical massage and stretching exercises were applied to the SCM-muscle in the SCM-Group. Treatment sessions were administered three times each week for a total of 5 weeks. Pain, endurance, ROM, disability, and kinesiophobia were evaluated. Both prior to and immediately following the treatments. Mixed-model repeated measured ANOVAs were then employed to determine if a group*time interaction existed on the effects of the treatment on each outcome variable for each group as the between-subjects variable and time as the within-subjects variables. RESULTS: Improvements in pain, disability, ROM(extension, left-lateral flexion, and right/left-rotation), and endurance were found to be greater in the SCM-Group compared to the CG (p < 0.05). Changes in flexion and right-lateral flexion ROM and kinesiophobia did not significantly differ between the groups (p > 0.05). CONCLUSION: Stretching exercises and massage applied to the SCM-muscle, together with conventional physiotherapy, can reduce pain and disability, and increase ROM and endurance in individuals with CNP. This treatment may therefore be considered for use as an alternative method in treating CNP. The study was registered in ClinicalTrials.gov (NCT04345042).