Introduction: Knee osteoarthritis (KOA) is characterized by pain, stiffness, and functional limitation. Aerobic exercise (AE) is a key treatment with proven benefits. Aims: To determine the most effective AE intensity for KOA. Methods: Searches were performed in seven databases, including randomized controlled trials with AE-only groups. Outcomes assessed were pain, walking and sit-to-stand performance, stiffness, and disability. Methodological quality and bias were evaluated. Bayesian random-effects network meta-analyses compared AE intensities, reporting standardized mean differences (Hedges’ g) with 95% credible intervals. Certainty of evidence was rated using GRADE. Results: Fifteen studies were included (mean PEDro score: 5.93), showing “some concerns” or “high risk” of bias. Two meta-analyses (pain and walking performance) were conducted. Comparisons between AE intensities showed non-significant, imprecise results with very low certainty of evidence. Conclusions: Evidence is insufficient to identify the optimal AE intensity for KOA. Limitations include high risk of bias, wide credible intervals, and reliance on indirect comparisons. In this context, clinicians should apply a structured, patient-centered approach to AE prescription, considering gradual progression and monitoring of tolerance, and combine AE with other recommended interventions. High-quality trials with direct comparisons of AE intensity should be conducted for this inconclusive gap.