[3] De Adder began his career working for The Coast, a Halifax-based alternative weekly, drawing a popular comic strip called Walterworld which lampooned the then-current mayor of Halifax, Walter Fitzgerald.

He draws approximately ten cartoons weekly and, at over a million readers per day, is considered the most read cartoonist in Canada.

In June 2019, de Adder had his freelance contract with Brunswick News, Inc. (BNI) terminated following his drawing of a cartoon criticising U.S. President Donald Trump's border policies.

The cartoon showed President Trump playing golf and ignoring the dead, face down, drowned bodies of two Mexican migrants.

Brunswick News issued a statement saying that they had not been offered the cartoon, and that the decision to replace de Adder with another cartoonist had been made some weeks previously.