is a Latvian composer and conductor. His mother is actress Zane Janczewska.Studied at Riga French Lyceum. At the same time, he studied piano at the 1st Music School in Riga and composition with Ilze Arnes. In 2008, he started studying conducting at the Riga Cathedral Choir School; graduated from school in 2012. In parallel with his studies, he studied composition with Paula Dambja and Ārik Ešenvald at the Riga Dome Choir School. In 2012, he entered the Jāzeps Vītolas Academy of Music of Latvia to study composition with professor Selgas Mence. He received his master's degree in composition from Jānis Petraškevičs.Jančevskis works as a conductor in the "Anima Mea" choir, teaches composition at the Riga Cathedral Choir School.As a child, he acted in several theater performances, also starred in films, including "The Ruined Nest".In 2019, Jančevskis won the main prize with the composition "When" in the group of participants under the age of 30 at the UNESCO International Young Composers' New Works Show "Rostrum" in Argentina.At the beginning of 2020, together with the conductor Jurgis Cābuli and the mixed choir of the Riga Dome Choir School, Jēkabs released his first choral music album on the British record company "Hyperion".