Background: We aimed to evaluate the effect of an 8-week yoga intervention on the shoulder and spinal actions of women with breast cancer-related arm lymphoedema. Method: A randomised controlled pilot trial. The intervention group (n = 12) completed eight weeks of daily yoga sessions while the control group (n = 11) continued with best current care including information on compression sleeves, skin care, risks of temperature variations and recommended safe use of affected arm. Lumbo-pelvic posture, range of motion (ROM) in the shoulder and spine, and strength in shoulder and pectoral major and minor, and serratus anterior were taken at baseline, week 8 and after a 4-week follow-up. Outcome assessors were blinded to allocation. Results: At week eight the intervention group had an improvement in lumbo-pelvic posture, as indicated by a reduction in pelvic obliquity compared to the control group (mean difference = -8.39°, 95 % CI: -15.64 to -1.13°, p = 0.023). A secondary finding was that strength in shoulder abduction significantly increased following the yoga intervention in both the affected (9.5 kg; CI: 0.34 to 18.66, p = 0.042) and non-affected arm (11.58 kg; CI: 0.25 to 22.91; p = 0.045). There were no significant between group changes in any ROM measures as a result of the yoga intervention. Conclusion: This pilot study demonstrates that participation in yoga may provide benefits for posture and strength in women with Breast Cancer Related Lymphoedema. The improvements may be attributed to the focus of yoga on overall postural and functional movement patterns. Further trials with longer intervention that follow this methodology are warranted. Trial registration: The Australian New Zealand Clinical Trials Registry ACTRN12611000202965.