Background: There are over 1.3 million colorectal cancer (CRC) survivors in the United States, and many of whom suffer from lower health-related quality-of-life (HRQoL) years after diagnosis and treatment. Physical activity may improve survival outcomes and HRQoL for CRC survivors. Feasible interventions to support physical activity after CRC diagnosis are needed. Methods: We conducted a two-arm randomized controlled trial of 41 men and women who had completed treatment for CRC. Participants in the intervention arm were given a Fitbit Flex™ and received daily text messages for 12 weeks. HRQoL was assessed in both arms at baseline and 12 weeks using the RAND Short Form Survey (SF-36) and the Functional Assessment of Cancer Therapy – Colorectal (FACT-C). Survey score changes from baseline to 12 weeks were compared between the two arms using independent t-tests, and scores at baseline and 12 weeks were compared using paired t-tests. SAS was used for analysis, and statistical significance was declared at p < 0.05. Results: We observed a statistically significant increase in the FACT-C functional well-being sub-scale in individuals in the intervention arm pre- and post- intervention (mean ∆ 1.81 ± 2.76; p: 0.02). There was no change in functional well-being in the control arm (mean ∆ -0.35 ± 4.12; p: 0.71). The between-arm comparison of change from baseline to 12 weeks was not statistically significantly (p: 0.08). There was a statistically significant increase in the FACT-C emotional well-being sub-scale in the control arm (mean ∆ 1.20 ± 2.48; p: 0.04) and in the SF-36 role physical sub-scale in the control arm (mean ∆ 22.5 ± 38.8; p: 0.02). No other measures of HRQoL were statistically significantly different within groups, across time points, or between groups. Conclusions: A 12-week physical activity intervention using a Fitbit Flex™ and daily text messages may improve functional well-being among CRC survivors. Larger randomized studies are needed to definitively determine if a digital physical activity intervention improves functional well-being among CRC survivors, and if the improvement can be sustained over time. Clinical trial information: NCT02966054