Background: Knee osteoarthritis (OA) is a widespread multifactorial joint condition that causes persistent pain and functional problems. It is distinguished by the degeneration of cartilage in joints, resulting in stiffness, discomfort, and diminished movement. The study aimed to evaluate the effect of educational module about heat therapy on pain and morning stiffness among patients with knee osteoarthritis. To carry out the current inquiry, a quasi-experimental approach was used. Setting: The research was carried out at the Orthopedic Outpatient Clinics at Suez Canal University Hospitals. Subjects: A total of (80) adult patients, with 40 assigned to the (control group) and 40 assigned to the heat treatment (case group) were involved in the research study. Tools of data collection: Two tools were used; Tool I, A structured interview questionnaire that used to measure demographic data and patient awareness of the disease; Tool II, self-administered Knee Injury and Osteoarthritis Outcome Score (KOOS), which was used to assess patient-relevant outcomes following knee injury. Results: The study found that joint pain and stiffness were the most common symptoms in the heat and control groups, respectively with (80% and 97.5%) and (32.5% and 57.5%). Heat therapy had a strong favorable effect on pain relief, stiffness relief, and physical function improvement by (10.76) pre and post application with statistically significant difference between two groups. Conclusion: Heat therapy had a positive effect on pain relief and morning stiffness in people with knee osteoarthritis with statistically significant difference. Recommendations: Assess the effect of physical exercises on knee osteoarthritis.