Ernie already had 8 years of comics experience in the Philippines, when in 1970 he migrated to Oakland,California. 

A fellow Philippine artist,Tony Dezuniga got him to move to New York and work for DC Comics in 1972.  He started illustrating mystery stories and later became regular on Batman for 2 years.  He also worked on Claw, Sandman (1974), Swamp Thing, Jonah Hex, and did a lot of covers.

He became a U.S.  citizen in 1976, and changed his name from Ernie Chua to Ernie Chan.  He explained that the former name was a typo on his birth certificate.

Working for Marvel Comics for 20 years, he had the longest stint on Conan, not counting the 2 years run of the syndicated Conan strip.  He also did other books like Hulk, John Carter of Mars, Doc Savage, Doctor Strange, Daredevil, Dracula, Fantastic Four, Thor, etc.

Ernie moved back to Oakland, California in 1980 for the weather and to be near his relatives.  He quit comics in 1995 to indulge in computer by working in video games, animation and movies, for companies like Sierra-on-line, Sega of America, Hanna Barbera, etc.

His chores ranges from storyboards, background design and rendering of character concepts.