Heyer was born in Haarhausen, Westphalia in 1872. He was both a painter and an illustrator. Heyer studied at the Berlin College of Arts and Crafts and in 1896 he moved to Rakospalota near Budapest where he remained for the rest of his life.

Heyer originated as a landscapist but soon moved on to painting animals particularly sentimental depictions of cats. He liked to paint white Persians which explains their predominance in his work. Heyer provided illustrations for the publication of the Franklinische Verlag which were mainly animal picture books. He also executed illustrations for Stettenheims's 'Weespen' and Shver's 'Familieblatt' and 'über Land und Meer'.

He died in Rakospalota, Budapest in 1931 at the age of 59.