Purpose <p>To longitudinally assess fatigue, physical and daily activity, and work ability 7 years post therapy in a radiotherapy-treated cohort, and to compare the long-term data with matched non-cancer referents from the general population.</p> Methods <p>A questionnaire assessed fatigue, concurrent symptoms, and physical and daily activity including work ability during radiotherapy and at a 7-year follow-up. For comparison, randomized matched population referents were included at the corresponding time point for each cancer survivor’s follow-up and responded the same questionnaire once. Generalized linear mixed models identified factors predicting and associated with fatigue and work ability at follow-up among survivors.</p> Results <p>Of 221 cancer survivors (49% females; mean age 72 ± 11&#xa0;years; 39% breast, 42% prostate, 20% other cancers) and 241 referents, survivors reported less fatigue over time but still more than referents (prevalence 58% vs. 41%, <i>P</i> = 0.001; score 2.1 vs. 1.3, <i>P</i> = 0.001). Their physical and daily activities improved to levels similar to referents. Working survivors reported lower self-perceived work ability (<i>P</i> = 0.016) and percentage of full-time work (<i>P</i> = 0.005). Fatigue during radiotherapy predicted fatigue at follow-up independent of depressed mood, pain, and number of concurrent symptoms. Among working survivors, fatigue was associated with poorer work ability, whereas being female, higher work self-efficacy, and work-related well-being were associated with better work ability.</p> Conclusion and implication <p>Fatigue during treatment may be an early indicator for persistent fatigue in cancer survivors, which may be related to reduced work ability. Long-term cancer survivors reported worse fatigue compared with referents. Future studies are warranted to examine whether early identification and supportive strategies may influence later fatigue and its potential implications for work ability in cancer survivors.</p>