We conducted a randomized controlled trial to determine the effects of a home-based exercise intervention on change in quality of life (QOL) in recently resected colorectal cancer survivors, most of whom were receiving adjuvant therapy. Participants were randomly assigned in a 2 : 1 ratio to either an exercise (n = 69) or control (n = 33) group. The exercise group was asked to perform moderate intensity exercise 3–5 times per week for 20–30 min each time. The primary outcome was change in QOL as measured by the Functional Assessment of Cancer Therapy-Colorectal (FACT-C) scale. Adherence in the exercise group was good (75.8%) but contamination in the control group was problematic (51.6%). Intention-to-treat analysis revealed no significant differences between groups for change in the FACT-C (mean difference, −1.3; 95% CI, −7.8 to 5.1; P = 0.679). In an ‘on-treatment’ ancillary analysis, we compared participants who decreased versus increased their cardiovascular fitness over the course of the intervention. This analysis revealed significant differences in favour of the increased fitness group for the FACT-C (mean difference, 6.5; 95% CI, 0.4–12.6; P = 0.038). These data suggest that increased cardiovascular fitness is associated with improvements in QOL in colorectal cancer survivors but better controlled trials are needed.