Background: Health behavior changes including tobacco cessation and increasing physical activity (PA) are important aspects of cancer survivorship. Understanding how these behaviours impact on HU and financial toxicity will help when evaluating survivorship programs. We evaluated the impact of tobacco cessation and PA on HU, function and financial toxicity among HNC patients (pts). Methods: HNC pts from Princess Margaret Cancer Centre completed questionnaires at baseline (diagnosis) and 12 months between 2014-2018 evaluating tobacco use, PA with the Godin questionnaire, cancer related monthly out of pocket costs (OOPC), HU using HU Index Mark 3, function using Lawton Brody Scale (LBS) and lost annual income. Multivariable linear regression analyses evaluated the impact of health behaviour change on OOPC, HU, LBS and lost income. Results: Among 296 pts, mean age 61, 76% male; 29% smoked at diagnosis, 60% quit 1 year after; 26% met PA guidelines at diagnosis, 52% continued to meet guidelines at 1 year. 19% of those not meeting PA guidelines at diagnosis, met them at 1 year. Among all, mean HU [SEM] was 0.84 [0.01] (baseline), 0.80 [0.01] (12 months); mean monthly OOPC [SEM] were $171 [27] (12 months); mean annual lost individual income was $25897 [2945]. Among smokers at diagnosis, those continuing to smoke at 1 year lost a mean of $21272 (95% CI [$2783-39761] P= 0.03) more in individual annual income compared to pts who quit, adjusted for baseline income and education. Current smokers who quit smoking at 1 year had an adjusted mean increase in HU of 0.15 ([0.00-0.30] P= 0.05) greater than pts continuing to smoke. Pts who continued meeting PA guidelines at 1 year had an adjusted mean increase in HU scores of 0.11 ([0.02-0.20], P= 0.02) compared to those reducing PA levels after diagnosis. Changes in PA and tobacco were not associated with change in function or OOPC; improving to meet PA guidelines after diagnosis was not associated with HU or lost income (P> 0.05). Conclusions: Quitting smoking and maintaining PA levels after diagnosis were associated with improvements in HU scores; quitting smoking reduced lost income. Cancer survivors should be made aware of the potential economic impact of behaviour change.