We report the characterization of two planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-1199 b and TOI-1273 b, with periods of 3.7 and 4.6 days, respectively. Follow-up observations for both targets, which include several ground-based light curves, confirmed the transit events. High-precision radial velocities from the SOPHIE spectrograph revealed signals at the expected frequencies and phases of the transiting candidates and allowed mass determinations with a precision of \(8.4\%\) and \(6.7\%\) for TOI-1199 b and TOI-1273 b, respectively. The planetary and orbital parameters were derived from a joint analysis of the radial velocities and photometric data. We find that the planets have masses of \(0.239\,\pm\,0.020\,M_{\mathrm{J}}\) and \(0.222\,\pm\,0.015\,M_{\mathrm{J}}\) and radii of \(0.938\,\pm\,0.025\,R_{\mathrm{J}}\) and \(0.99\,\pm\,0.22\,R_{\mathrm{J}}\), respectively. The grazing transit of TOI-1273 b translates to a larger uncertainty in its radius, and hence also in its bulk density, compared to TOI-1199 b. The inferred bulk densities of \(0.358\,\pm\,0.041\,\mathrm{g}\,\mathrm{cm}^{-3}\) and \(0.28\,\pm\,0.11\,\mathrm{g}\,\mathrm{cm}^{-3}\) are among the lowest known for exoplanets in this mass range, which, considering the brightness of the host stars (\(V \approx 11\,\mathrm{mag}\)), render them particularly amenable to atmospheric characterization via the transit spectroscopy technique. The better constraints on the parameters of TOI-1199 b provide a transmission spectroscopy metric of \(134\,\pm\,17\), making it the better suited of the two planets for atmospheric studies.