Intra-articular injections with hyaluronic acid are recommended in the treatment of knee osteoarthritis; however, hypertonic dextrose prolotherapy has been reported as effective and safe. The aim was to evaluate the effectiveness of hypertonic dextrose prolotherapy for pain reduction and improvement of function in individuals with knee osteoarthritis in comparison with hyaluronic acid by meta-analysis. The search was performed in electronic databases. Six studies were included (395 participants). No statistically significant differences were found between prolotherapy and hyaluronic acid in pain control in the short-term; however, in the subanalysis that included only the studies that used intra-articular injection within the prolotherapy scheme, an effect was found in favor of the prolotherapy groups (d = −1.33; 95% confidence interval, −2.50 to −0.16; P (z) = 0.03). Also, an effect was found in favor of the prolotherapy group in the improvement in function (d = −1.05; 95% confidence interval, −2.03 to −0.08; P (z) = 0.03). No major adverse reactions or side effects were reported in any of the studies. Hypertonic dextrose prolotherapy seems to be an effective intervention to decrease pain and improve function in knee osteoarthritis, with efficacy similar to intra-articular injections with hyaluronic acid in the short-term follow-up. Nonetheless, better-quality clinical trials are necessary.