Background Measurement of neck muscle strength is common during the assessment of people with chronic neck pain (CNP). This systematic review evaluates the measurement properties (reliability, validity, and responsiveness) of neck muscle strength measures in people with CNP. Databases and data treatment This systematic review followed a PROSPERO registered protocol (CRD42021233290). Electronic databases MEDLINE (OVID interface), CINAHL, SPORTDiscuss via (EBSCO interface), EMBASE (OVID interface), and Web of Science were searched from inception to 21 June 2021. Screening, data extraction, and quality assessment (Consensus-based Standards for the selection of Health Measurement Instruments (COSMIN) checklist) were conducted independently by two reviewers. The overall strength of evidence was evaluated using the modified Grading of Recommendations Assessment, Development and Evaluation. Results From 794 records, nine articles were included in this review which concerned six different neck strength outcome measures. All studies evaluated reliability and one evaluated construct validity. The reliability of neck strength measures ranged from good to excellent. However, the risk of bias was rated as doubtful/inadequate for all except one study and the overall certainty of evidence was rated low/very low for all measures except for the measurement error of a handheld dynamometer. Conclusion A multitude of measures are used to evaluate neck muscle strength in people with CNP, but their measurement properties have not been fully established. Further methodologically rigorous research is required to increase the overall quality of evidence.