Objectives: Adaptations in somatosensory function characterize several chronic pain conditions, including nonspecific neck pain (NNP). Early signs of central sensitization (CS) contribute to pain chronification and poor treatment responses after conditions such as whiplash injury and low back pain. Despite this well-established association, the prevalence of CS in patients with acute NNP, and accordingly, the potential impact of this association, is still unclear. Therefore, this study aimed to investigate whether changes in somatosensory function occur during the acute phase of NNP. Methods: This cross-sectional study compared 35 patients with acute NNP with 27 pain-free individuals. All participants completed standardized questionnaires and an extensive multimodal Quantitative Sensory Testing protocol. A secondary comparison was made with 60 patients, with chronic whiplash-associated disorders, a population wherein CS is well-established. Results: Compared with pain-free individuals, pressure pain thresholds (PPTs) in remote areas and thermal detection and pain thresholds were unaltered. However, patients with acute NNP showed lower cervical PPTs and conditioned pain modulation, higher temporal summation, Central Sensitization Index scores, and pain intensity. Compared with the group with chronic whiplash-associated disorders, PPTs did not differ at any location, yet the Central Sensitization Index scores were lower. Discussion: Changes in somatosensory function occur already in acute NNP. Local mechanical hyperalgesia demonstrated peripheral sensitization, while enhanced pain facilitation, impaired conditioned pain modulation, and self-reported symptoms of CS suggest adaptations in pain processing already early in the stage of NNP.