Klaas-Jan de Groot is a Dutch conductor and chorus master.

Since 2016 Klaas-Jan has worked at Dutch National Opera, where he assisted on many productions and was in charge of the chorus preparation for several productions and other smaller projects. He was chorus master at The Netherlands Radio Chorus for Nabucco (Verdi), Semiramide (Rossini), Il piccolo Marat (Mascagni) and Jenůfa (Janáček). At Opera Zuid (Maastricht) he has worked as repetiteur, chorus master and assistant conductor. He has also conducted full performances of Un ballo in maschera (Verdi) and Fantasio (Offenbach). In 2018 and 2019 he was assistant chorus master at the Bayreuther Festspiele (Fliegende Holländer, Tannhäuser, Lohengrin, Tristan & Isolde, Meistersinger, Parsifal). With the Orchestra of the Eighteenth Century he has served as assistant conductor for a semi-staged production of Don Giovanni (Mozart).
As chorus master he has prepared the Rotterdam Symphony Chorus for a recording of Beethoven IX with the Rotterdam Philharmonic Orchestra. At the Opera Studio of Dutch National Opera he has prepared the soloists for various projects and productions. 
In 2020 he was awarded the prestigious conducting scholarship of the Kersjes Fonds.

Born in 1993, Klaas-Jan started to play the piano at a young age. Around the age of 9 he started to sing as a boy soprano in the Kampen Boys Choir which was led by Bouwe Dijkstra. There he also received his first conducting lessons and decided this was what he wanted to do. In 2010 he started his conducting studies at the Royal Conservatory in The Hague. His teachers were Jos van Veldhoven, Kenneth Montgomery, Alex Schillings and Jos Vermunt. After his graduation in 2014, following a graduation concert with music by Bach and Stravinsky, he continued his studies at the Royal Welsh College of Music and Drama in Cardiff (UK). During his studies he was a singer in the choir of Llandaff Cathedral, the BBC National Chorus of Wales, and the BBC Proms Youth Choir. He finished his masters degree in 2015 after which he returned to The Netherlands to start working professionally.