The boy eventually left Soest when John I, Duke of Cleves hired him as a singer.
At Cleves, Johannes von Soest studied composition with an unknown teacher, quickly distinguishing himself as the best student and becoming, in his own words, a better composer than his master.
Although he had a large salary and a high reputation, by 1476 Johannes was apparently no longer satisfied with his musical activities.
No compositions by Johannes von Soest survive, but contemporary sources mention vocal music for 9 to 12 voices and other pieces.
His pupils included composer and theorist Sebastian Virdung, author of one of the earliest known German treatises on musical instruments.