Despite his early death he is remembered as a collector and commissioner of music and as a composer, some of whose concertos were arranged for harpsichord or organ by Johann Sebastian Bach, who was court organist in Weimar at the time.

From Utrecht, he could visit such centres as Amsterdam and Düsseldorf and it is known that he had copies of Italian music sent back to Weimar.

(Household bills for the year from 1 June following his return record the cost of copying, binding and shelving music.

The Bach transcriptions were created roughly during the period July 1713–July 1714 between Johann Ernst's return from Utrecht and the prince's final departure from Weimar.

There is some scholarly debate on Johann Ernst's role in the creation of these arrangements, whether he commissioned some from one or both of the musicians or whether Bach, in particular, was studying some of the works collected by the prince for their own sake.

There are suggestions that on a visit to Amsterdam in February 1713 the Prince may have heard the blind organist J. J. de Graff, who is known to have played keyboard arrangements of other composers' concertos.

[5] [6] As well as influencing Bach, Johann Ernst completed at least nineteen instrumental works of his own before his death at age eighteen.

[3][7][8] Johann Ernst died in Frankfurt after a long illness resulting from a leg infection, possibly a metastatic sarcoma, which, despite the intensive care of his heart-broken mother and medical treatments in Schwalbach, spread to the abdominal area.

Music was banned, including in church, resulting in an interruption in Bach's attempt to build an annual cycle of cantatas.

Adaptations: Sonata in D major for trumpet, two violins and continuo (attribution uncertain): Apart from several performances of the Bach transcriptions, recordings featuring music by Johann Ernst include: