After completing his doctorate, Mützenich joined the State Ministry of Labour, Health and Social Affairs of North Rhine-Westphalia.

In the negotiations to form a coalition government under the leadership of Chancellor Angela Merkel following the 2017 federal elections, Mützenich was part of the working group on foreign policy, led by Ursula von der Leyen, Gerd Müller and Sigmar Gabriel.

In June 2019, Mützenich became acting chairman of the SPD parliamentary group after the startling demission of Andrea Nahles.

[11] In 2015, Mützenich criticized SPD "rapprochement romantics" in Germany's relationship with Russia and warned against the "misconception that old-style Ostpolitik was possible following the annexation of Crimea.

[14] Due to his Russia policy and his attitude towards NATO Rolf Mützenich was repeatedly referred to as a "Russlandversteher" or "Putinversteher", which he always denies.