He was born and raised in Skagafjörður in northern Iceland. His father was a local schoolmaster. His much younger mother died from child labour when he was 9 years old.
When the time came, he eventually persuaded his father to allow him to pursue his artistic interests rather than the academic career pre-planned for him.
He studied art in Reykjavík and subsequently in Copenhagen in the late 1940s and early 1950s.
As a child Jóhannes demonstrated a talent for drawing and painting. Although he earned high remarks from his respected tutors, he initially had trouble making a living from his art after his homecoming, working mainly as an illustrator for advertisement agencies. Around 1965 the local art community started taking more notice of this little known young artist and his "dark, depressive" paintings.
Over the next few years he became one of the best known, best selling, and most respected painters in Iceland.
Success also spelled the end of his "depressive era". Instead he turned his attention to painting Icelandic landscapes, but now with his unique unmistakable style - characterized with bright shining colours depicting (or amplifying) the beauty of a sometimes dull landscape.
In the late 1970s, being an established successful artist, Jóhannes could divide some attention to one of his lifelong interests - The Viking Sagas - and incorporate them into his art Foreign the rest of his life, he made hundreds of illustrations based on the Sagas, ranging all the way from grand oil paintings to small pencil sketches.
Despite his failing health, Jóhannes kept on working until his dying day.
