Background: Total knee and hip arthroplasty (TKA/THA) remain standard treatments for end-stage osteoarthritis. Physical activity (PA) is critical for optimal functional outcomes during and after rehabilitation. Objective was to assess attitudes and practices of physical therapists (PTs) regarding PA in TKA/THA patients across Germany, Norway, and the Netherlands, and explore how background factors, including education and national healthcare settings, influence practices and recommendations. Methods: A cross-sectional survey was administered to PTs in Germany (n = 113), Norway (n = 83), and the Netherlands (n = 156). Background characteristics and responses were analysed using descriptive and chi-square statistics. Results: PTs from all three countries showed positive attitudes towards PA post-TKA/THA, with notable variations in approach. Norwegian PTs, the highest-educated, emphasised PA intensity and muscle strengthening. Dutch PTs reported the highest availability of PA program services in their clinics. German PTs were less familiar with WHO guidelines but provided personalised advice. Conclusion: PTs’ attitudes were positive but varied, possibly due to differences in education and national healthcare structure. Findings highlight the need for tailored education and cross-national knowledge-sharing to support effective PA integration into TKA/THA rehabilitation.