<p>The present work examines the impact of temperature mismatch on the power output of flexible paper-based thermoelectric generators (PTGs), with thermoelectric (TE) legs configured in series, parallel, and series–parallel arrangements. The PTGs were fabricated using <i>p</i>-type Bi_0.5Sb_1.5Te₃ (BST) and <i>n</i>-type Bi₂Te_2.7Se_0.3 (BTS) TE materials on flexible paper substrates. The investigation involved systematic measurements of the open-circuit voltage (<i>V</i>_oc), short-circuit current (<i>I</i>_sc), and maximum power output (<i>P</i>_max) under various temperature gradients (Δ<i>T</i>s). Results revealed significant differences in performance across configurations, with the series–parallel configuration demonstrating superior power output due to reduced temperature mismatches and minimized voltage/current losses. The obtained highest normalized power density was 6.19&#xa0;nW&#xa0;cm⁻²&#xa0;K⁻¹&#xa0;pair⁻¹. The study highlights the potential of PTGs for wearable electronics, emphasizing the importance of device configuration in optimizing energy harvesting efficiency. The results of this study contribute to the advancement of sustainable, self-powered systems that harness low-grade body heat and ambient Δ<i>T</i>s.</p> Graphical Abstract <p></p>