Purpose: It is unclear how physical therapists in Florida currently treat people with knee osteoarthritis and whether current best evidence is used in clinical decision making. Methods: We conducted a survey of physical therapists in Florida. We assessed the perceived effectiveness and actual use of physical therapy (PT) interventions and quantified the association between the actual use of interventions and different characteristics of physical therapists. Results: A total of 413 physical therapists completed the survey. Most respondents perceived therapeutic exercise (94%) and education (93%) as being effective or very effective. Interventions least perceived as effective or very effective were electrotherapy (28%), wedged insole (20%), and ultrasound (19%). Physical therapists who followed the principles of evidence-based practice were more likely to use therapeutic exercise (OR 3.89; 95% CI: 1.21, 12.54) and education (OR 3.63; 95% CI: 1.40, 9.43) and less likely to use ultrasound (OR 0.32; 95% CI: 0.16, 0.63) and electrotherapy (OR 0.32; 95% CI: 0.17, 0.58). Results also indicated that older physical therapists were more likely to use ultrasound (OR 3.57; 95% CI: 1.60, 7.96), electrotherapy (OR 2.53; 95% CI: 1.17, 5.47), kinesiology tape (OR 3.82; 95% CI: 1.59, 9.18), and ice (OR 1.95; 95% CI: 1.02, 3.73). Conclusions: In line with clinical guidelines, most physical therapists use therapeutic exercise and education to treat people with knee osteoarthritis. However, interventions that lack scientific support, such as electrotherapy and ultrasound, are still used. A modifiable therapist characteristic, adherence to evidence-based practice, is positively associated with the use of interventions supported by scientific evidence.