Kari's maternal grandfather was Finnish sculptor Emil Wikström, and his younger sister was the opera singer and director Saskia Suomalainen, a.k.a.

In 1950, he gave a proposal to the chief editor of Helsingin Sanomat that he would start drawing daily political cartoons, according to the example of foreign newspapers.

Suomalainen started drawing daily political cartoons in Helsingin Sanomat in the year 1951, during Juho Kusti Paasikivi's presidency.

One of Suomalainen's most favourite characters was Urho Kekkonen, whom he drew as a bald man with an angular chin and huge eyeglasses.

Suomalainen published a cartoon of himself weeping at Kekkonen's portrait, saying he "felt like a man who has just lost a gold mine".

Suomalainen and the newspapers editor-in-chief Janne Virkkunen had an quarrel in 1991, after Helsingin Sanomat refused to publish Kari's cartoons criticizing Somali refugees, because they were considered to be too racist.