Permafrost peatland lakes are an organic-rich subcategory of thermokarst lakes and ponds that are known for their high rates of greenhouse gas emissions (Matveev et al. 2016). This Nordicana D archive presents the concentrations of methane and carbon dioxide that were measured in waters sampled at different depths in thermokarst lakes of the Sasapimakwananisikw River (SAS) peatland valley (center of subarctic Québec, Canada), and in thermokarst lakes of the Boniface River (BON) peatland valley (north of subarctic Québec, Canada). Additional data are presented for profiles of the key limnological parameters, and continuous data are presented from moorings that were installed in SAS lakes from 2014 to 2016. For the methane and carbon dioxide profiles, the water was sampled with a water bottle, and the gases determined by headspace equilibration (details in Matveev et al. 2019). The water column profiles of other variables were determined with commercial multiparameter sondes. The continuous data were obtained with autonomous loggers (details in file descriptions).