Background Low-back pain (LBP) is highly prevalent among senior workers and may affect work ability, especially among those with hard physical work. This study determined the joint association of LBP intensity and physical work demands with work limitiations due to pain in senior workers. Methods In the SeniorWorkingLife study (2018), 11,738 senior workers (≥50 years) replied to questions about physical work demands, LBP intensity, and work limitations due to pain. Using logistic regression analyses and controlling for potential confounders, associations between the physical work demands and LBP intensity (interaction) with work limitiations due to pain (outcome) was modeled. Results Higher LBP intensity, as well as higher physical work demands, significantly increased the odds of experiencing work limitiations due to pain, and these two factors interacted with each other (p < 0.0001). In analyses stratified for LBP intensity, higher physical work demands gradually increased the odds of experiencing work limitiations due to pain. Conclusions Senior workers with a combination of physically demanding work and LBP are more affected by their pain during everyday work tasks compared to workers with similar LBP-intensity in sedentary occupations. Accommodation of work demands seems especially relevant for this group of workers.