Purpose The associations of physical activity and television (TV) viewing with mortality risk among individuals with hematologic malignancies remain unclear. Methods We examined the relations of physical activity and TV viewing time before and after diagnosis with mortality among 5182 U.S. adults aged 50-71 years from the NIH-AARP Diet and Health Study cohort who survived a first primary hematologic cancer between 1995-1996 and 2011. Results For the pre- and post-diagnosis analyses, we confirmed 2606 and 613 deaths respectively. In multivariable-adjusted Cox proportional hazard regression models, comparing high (>= 4 hrs/wk) versus low (<1 hr/wk) activity levels, pre-diagnosis physical activity was associated with 18%-22% reduced risks of all-cause mortality among all hematologic cancer survivors, and survivors of non-Hodgkin lymphoma, myeloma, and leukemia, respectively. Additional control for BMI had little impact on the results, expect for myeloma survivors, for whom the association was no longer significant. Post-diagnosis physical activity was related to risk reductions in mortality ranging from 36%-47%. The associations for TV viewing did not show a clear pattern. Conclusion Our study suggests that pre- and post-diagnosis physical activity is associated with lower risk of all-cause mortality among hematologic cancer survivors. Further research is required to confirm this observation.