Kammala jumla mai zuwa: A cikin 1776, Tyszkiewicz ya kasance wakili ga Sejm daga Vilnius Voivodeship. kuma a cikin 1778 an sanya shi Marshal na Sejm. A shekara ta 1782, ya kasance mai goyon bayan Majalisar Dattijai. A lokacin da
Yakin Poland-Rasha na 1792, a taron da aka yi a ranar 23 ga Yuli, ya goyi bayan shigar da sarki cikin Targowica Confederation, wanda misalinsa Tyszkiewicz da kansa ya bi, ya zama Babban Marshal na Lithuania. A lokacin Grodno Sejm, an zaɓe shi a matsayin mai sasantawa tare da jakadan Rasha Jacob Sievers, don haka a ranar 22 ga Yuli 1793 ya rattaba hannu kan yarjejeniyar ba da ƙasa ga Rasha, sannan a ranar 25 ga Satumba zuwa Prussia, a matsayin wani ɓangare na Raba na Biyu na Poland. A cikin 1795, ya kasance shugaban ƙungiyar Lithuania da ke ba da girmamawa ga Catherine II.