Background and Objectives: Percutaneous Electrical Stimulation (PES) interventions, particularly percutaneous neuromodulation (PNM) and electroacupuncture (EA) techniques, have shown potential in targeting neuromusculoskeletal tissues, primarily for improving pain and functionality. Regarding functionality, this study specifically aims to analyze the impact of PES interventions on active muscle functionality in both healthy individuals and those with neuromuscular pathologies. Methods: A systematic review was registered in PROSPERO (CRD42024605747) following PRISMA guidelines. A literature search was conducted in July 2024 across PubMed, Cochrane, BVS, Science Direct, Web of Science, and Scopus. Included studies were randomized controlled trials in which a group received an isolated PES intervention and variables related to active muscle functionality were addressed (e.g., strength, endurance, contractile properties). Methodological quality was assessed using the PEDro scale, and the risk of bias was evaluated with the RoB2 tool. Results: A total of 359 participants from 8 studies were included. Regarding active muscle functionality variables, 5 studies targeted strength, 1 study assessed endurance, 1 study evaluated contraction time, and 1 study examined nerve excitability. PES demonstrated positive effects on all variables except contraction time, where PES was no more effective than non-percutaneous interventions. Discussion: PES interventions are suggested to be effective for enhancing active muscle functionality, particularly in individuals with neuromusculoskeletal conditions who are more likely to present muscle impairments. However, these findings should be interpreted with caution due to significant heterogeneity in PES protocols, comparators, and study populations, making direct comparisons between studies challenging. Conclusions: PES, including EA and PNM interventions, is an effective approach for enhancing active muscle functionality, specifically in terms of maximum isometric strength, endurance, and nerve excitability, in both healthy individuals and populations with musculoskeletal pathologies. Further research is needed to establish standardized PES application protocols in rehabilitation settings.