Leonie Wesselow was born in Hamburg in 1998. She started taking singing and dancing lessons as a child, and at the age of twelve, she made her stage debut in a school play. She made her first TV appearance in a 2010 episode of the children's TV show "Das Haus Anubis". From 2013 on, she attended acting workshops at the Hamburg Stage School and the Joop van den Ende Academy. Following her turn in the short "Das Mädchen ohne Hände" (2014), Wesselow was cast as one of the leads of the feature film "Back for Good", which premiered at the 2017 Berlin IFF. Since 2014, Wesselow has also been appearing in several plays at the Thalia Theater, and in 2017, she played the character of Belle in a Hamburg musical production of "The Beauty and the Beast".

When "Back for Good" was released theatrically in May 2018, Wesselow was in the middle of shooting the TV thriller "Flucht durchs Höllental", directed by Marcus O. Rosenmüller.