Muscle and tendon injuries are prevalent occurrences during sports activities. Platelet-rich plasma (PRP) is known for its rich content of factors essential for wound healing, inflammation reduction, and tissue repair. Despite its recognized benefits, limited information is available regarding PRP’s effectiveness in addressing combined surgical injuries to the gastrocnemius muscle and Achilles tendon. The effects of PRP on muscle and tendon injury in rats were assessed through a set of biochemical markers, histopathological examinations, and immunohistochemistry analyses of muscular myogenin, desmin, and tendinous type I collagen. Additionally, mRNA expression levels of Matrix metalloproteinase-9 (MMP-9), Pro-apoptotic Bcl-2 Associated-X-protein (BAX), Insulin-like growth factor (IGF), and High mobility group box 1 protein (HMGB1) genes were evaluated. In duction of muscle and tendon injuries was associated with elevated levels of serum biomarkers such as C-reactive protein (CRP), Aspartate aminotransferase (AST), Lactate dehydrogenase A (LDH), and Creatine Kinase MB (CK MB), delayed collagen fiber remodeling, and structural abnormalities in myofibrils. Furthermore, there was overexpression of MMP9, Bax, and HMGB1 genes, along with decreased expression of the IGF gene in this group. Treatment with PRP resulted in significant improvement of these reported findings, including enhanced collagen fiber remodeling, elevated levels of desmin and myogenin in muscle tissues, and increased expression of collagen type I in tendons. Additionally, PRP treatment led to reduced expression levels of MMP9, Bax, and HMGB1 genes, while the expression of the IGF gene increased. Overall, PRP treatment demonstrated substantial enhancement of the healing process in both muscle and tendon tissues in a surgical model of gastrocnemius skeletal muscle and Achilles tendon-induced injury. These findings suggest that PRP therapy may offer advantages in the treatment of physical-related injuries.