In this study, we investigate the gravity changes (g˙) associated with the Glacial Isostatic Adjustment (GIA) and their correlation with land uplift rates (h˙) using GRACE and GRACE Follow-on data, spanning 2003 to 2023. We further validate our results using repeated absolute gravity measurements. We analyze the absolute gravity measurements collected in Canada and Fennoscandia since the 1990s and 1960s, respectively. The novelty involves applying the Sjöberg and Bagherbandi (2020) methodology to Canadian data using GRACE-derived upper mantle density and comparing the results with the terrestrial absolute gravimetry results. One of the aims of this study is also to assess the methods effectiveness in Canada, as was previously done in Fennoscandia. In addition, this study explores the similarities and the relationship between the gravity field change with other Earth's interior parameters (e.g. density, viscosity, etc.), that offers new insights into their potential connections and understanding regional geodynamics. For Canada, we process the raw gravity observations, considering instrument precision and weighting, applying systematic corrections (Earth tides, polar motion, ocean loading, and atmospheric pressure effects), standardizing measurements to a uniform height using the vertical gravity gradient correction, implementing a rigorous drop selection and filtering process, and using a filter to minimize short-term environmental variations. For Fennoscandia, we use the processed absolute gravity data published by Olsson et al. (2019). We also estimate upper mantle density, associated with viscous mass flow in the mantle, and temporal variations in surface gravity changes (g˙) using GRACE and GRACE-FO data. Finally, the obtained g˙/h˙ ratio is calculated to be compared with terrestrial absolute gravity measurements and also compared with the previously published results to assess the obtained outcomes. The results derived from GRACE and GRACE Follow-on data show that the ratios between surface gravity and height changes are −0.152 ± 0.010 μGal/mm in Canada and −0.156 ± 0.016 μGal/mm in Fennoscandia aligning closely with findings from terrestrial gravity observations. These values correspond to upper mantle densities of approximately 3736 ± 239 kg/m3 and 3641 ± 382 kg/m3 in Canada and Fennoscandia, respectively.