Objective: The objective was to assess the effectiveness of a volunteer-delivered tailored telephone-based intervention in reducing prevalence of unmet supportive care needs, elevated levels of anxiety and depression among people with colorectal cancer over a 9-month period. Methods: There were 653 participants who completed the baseline questionnaire and were randomised to usual care (n = 341) or intervention (n = 306). Three follow-up questionnaires were completed at 3-monthly intervals (response rates: 93%, 87%, 82%, respectively). All four questionnaires contained the Supportive Care Needs Survey (SCNS), Hospital Anxiety and Depression Scale (HADS) and checklists for colorectal cancer symptoms and use of support services. The intervention consisted of trained volunteers providing emotional support, service referral and information and was delivered after completion of each of the first three questionnaires. Primary outcomes were prevalence of moderate to high SCNS needs and elevated levels (scores of 8+) of HADS anxiety and depression. Results: Over the study period, SCNS needs decreased similarly for both groups, and prevalence of elevated depression did not change for either group. There was a greater reduction in the prevalence of elevated anxiety in the intervention than usual care group (p < 0.01), with the intervention group decrease mainly occurring between baseline and the first follow-up survey (p < 0.01). However, the prevalence of elevated anxiety was similar between the two groups at each follow-up point. Conclusions: The intervention had no effect on supportive care needs or depression, although it may be associated with a greater reduction in anxiety. Future research should test the intervention with patients closer to diagnosis.