This original study reveals the complex relationships between teleworking conditions (the proportion of time spent teleworking and four non-exhaustive material conditions: having a dedicated workspace in the home, a second computer monitor, an office chair, and a keyboard) and the onset of low back pain. It takes into account depressive symptoms during the third lockdown due to the COVID-19 crisis, which was in effect from April 3 to May 2, 2021, in France. Based on two waves of the CoviPrev survey conducted online among the general population (in June and July 2021), structural equation models were applied to the 466 individuals who reported working from home at least one day per week during the lockdown and who did not have low back pain at the start of the lockdown. The prevalence of low back pain onset appeared to vary, albeit not significantly, depending on the weekly proportion of telework, ranging from 9% for full-time telework to 5% for hybrid work (part-time telework). The physical conditions of remote work and the proportion of remote work were significantly associated with the level of satisfaction with remote work conditions. This same level of satisfaction was significantly associated with a lower risk of depressive symptoms and the onset of low back pain. Furthermore, the presence of depressive symptoms was also significantly associated with the onset of low back pain during the third lockdown. These results provide a better understanding of the chain of determinants leading to the onset of low back pain in a teleworking context. In addition to satisfaction with working conditions, these results highlight the importance of the physical setup for remote work (dedicated room, second screen, keyboard, office chair) as well as certain aspects of work organization, such as the proportion of time spent working remotely, in reducing the health impacts of remote work. As regular telework becomes established over the long term and profoundly alters work organization within sectors where it is feasible, these findings help identify effective levers for action to mitigate the health consequences of telework or hybrid work. Furthermore, combating sedentary behavior—particularly during telework—is also essential for reducing the impact of working conditions on workers’ health.