At the age of five Niels Pfeffer began to play the classical guitar and was soon being taught by Prof. Johannes Monno at the Music University of Stuttgart. Prof. Carsten Lorenz, with whom he took additional harpsichord lessons, also taught him continuo playing and introduced him to the art of historical performances. In 2017 he finished his harpsichord studies at the Stuttgart University of Music under Prof. Jörg Halubek and his guitar studies with Prof. Johannes Monno. Currently he is studying harpsichord in master with Prof. Robert Hill in Freiburg as well as with Prof. Zoran Dukić in The Hague (guitar). In The Hague he additionally studies theorbo with Mike Fentross and Joachim Held.

With the guitar Niels Pfeffer won numerous prizes at renowned international competitions (1st prize Anna-Amalia competition in Weimar, 2013, 2nd prize guitar competition Nürtingen 2014, five prizes at the Andres-Segovia competition in Velbert, 2007, 2009, 2011, 2013 and 2015, third prize in Kutná Hora 2015, fourth prize in Bratislava 2016, finalist and special prize at Forum Gitarre Wien 2016).

Niels Pfeffer is passionate about playing continuo on harpsichord and theorbo. With both instruments he was taking part in various opera performances – including Händel’s Rodrigo and Rodelinda (Stuttgart) and Reinhold Keisers' Octavia (Innsbruck). Antonio de Literes’ opera Los Elementos led him to the Kassel state theatre, where he was engaged as a musical assistant for the stage rehearsals. In summer 2018 he was playing continuo in the operá-ballet production Solen och Nordstjärnen in Vadstena, Sweden. He played with numerous orchestras, including the Nordic Baroque Orchestra led by Rachel Podger as well as the Rotterdam Philharmonic Orchestra directed by John Butt. As member of the ensembles La Serenité, Le Tic-Toc-Choc and Bryggan he has been regularly successful in early music competitions: Carl Wendling competition 2014, Händel competition in Karlsruhe 2015 and 2016, competition for Early Music of the Saarländischer Rundfunk 2017 and Premio Selifa in San Ginesio 2018. In 2019 he won the third prize at the International Basso Continuo and Partimento Competition in Katowice, Poland. He took part in masterclasses with Konrad Junghänel, Skip Sempé, Frederic Haas, Beatrice Martin and many more.

In the winter term 2017/18 he was teaching as harpsichord accompanist at the University of Music Stuttgart. Since summer term 2018 he is teaching continuo and theorbo at the same University. Furthermore, Niels Pfeffer is currently working as a co-editor on the continuo realisation of Monteverdi’s Poppea, which will be published by Bärenreiter.

Recordings for public television and radio stations led Niels Pfeffer multiple times to Estonia, the Lebanon and Armenia. During his studies in Stuttgart he received a scholarship of Live Music Now. Furthermore he was granted in 2014 the well-known Deutschlandstipendium scholarship and in 2017 as well as 2018 the Excellence Scholarship of the Royal Conservatory Den Haag.