Research highlights the importance of maintaining pre-diagnosis physical activity levels for breast cancer survivors post-treatment. However, many survivors have difficulty engaging in physical activity due to cancer-related fatigue. The aim of this study was to explore how participation in a 12-week yoga intervention impacted fatigue and physical activity. 20 individuals with breast cancer diagnosis participated in a 12-week yoga intervention. The yoga intervention included modified hatha yoga postures and consisted of 10 min. of warm-up, 45 min. of yoga postures, 10 min. of breath work, and 10 min. of supine resting pose (savasana), for a total of 75 min. Assessments were administered at 3 time points: pre (T1), post (T2) yoga intervention and at a 12-week follow-up (T3). Measures included self-reported fatigue (Cancer Fatigue Scale) and physical activity (accelerometer step counts). One-way ANOVA were used to examine how fatigue scores and steps counts were changed over the course of the intervention. Total fatigue score (FS) and daily step (DS) counts at each time point were T1 (FS=21.6±8.9, DS=7709±2036), T2 (FS=14.0±8.3, DS=8429±2722), and T3 (FS=16.8±6.9, DS=8406±3389). Significant improvements in physical fatigue T1 (p<0.05, η² = 0.14) and cognitive fatigue (p<0.01, η² = 0.11) were seen at T1-T2. No significant changes were seen in psychological fatigue. 12 participants (65%) had high fatigue levels at T1, which decreased to 5 participants (27.8%) at T2. 12 participants (66.7%) increased daily steps at T2 and 8 participants (44.4%) continued to increase at T3. There were negative correlations between fatigue scores and step counts at all time points (r=-0.45~-0.55). Participation in a 12-week yoga program was associated with improved cancer-related fatigue.