During his law studies at the University of Leipzig, he worked for Barbara Höll and Heidemarie Lüth, who were members of the German Bundestag at the time.

While his vote fell slightly to 22.8%, his margin increased to 4.4% as the second-placed candidate, Paula Piechotta of the Greens, won 18.4%.

Pellmann's re-election was especially significant since The Left won only 4.9% of votes nationally, just short of the 5% electoral threshold, and was only entitled to proportional representation due to winning three constituencies: Berlin-Treptow-Köpenick, Berlin-Lichtenberg, and Leipzig II.

After the Russian invasion of Ukraine in February 2022, he and five other Left MdBs joined Wagenknecht in issuing a joint statement attributing responsibility for the war in part to the United States and NATO.

[6] In February 2024, Pellmann was elected co-leader of the Left's reorganised Bundestag group alongside Heidi Reichinnek, defeating Clara Bünger 14 votes to 13.