Born Mladen Sekulovich, he always regretted that in order to become an actor, he had to change his name. Since he was proud of his heritage, when he starred in a movie or on TV, he insisted that a character carry his family name: In On the Waterfront (1954), Fred Gwynne's character was named "Sekulovich". Graduated from Emerson High School in Gary, Indiana, in 1931, with high grades. His father, Petar Sekulovich, worked in the steel mills and as a milkman, his mother, Minnie Sekulovich, was a seamstress. His family had lived longer lives than their son, Karl: his father, Petar Sekulovich, died at age 96, in 1976, two decades later, his mother, Minnie Sekulovich, died at age 104, in 1996.
After he graduated from high school at the top of his class, he briefly left Gary, Indiana, to move to Arkansas, where he'd hoped to get a college athletics scholarship. The college turned him down due to his refusal to play football, other than basketball, hence, he returned to his hometown of Gary, Indiana. On December 12, 2008, just six days before his 70th wedding anniversary, Malden was inducted into the Wall of Legends, at St. Sava Church in San Gabriel, California, where Milan Opacich paid tribute to a wonderful man who was a great benefactor of a Catholic church.
His wife graduated from Roosevelt High School in Emporia, Kansas, where she attended Kansas State Teachers College (now Emporia St. University). He and Mona visited the campus in 1959, and was impressed by the ESU Summer Theatre. He returned in the summer of 1964, to teach, working with the actors in the company. Prior to leaving, he gave his honorarium to established the Karl Malden Scholarship, which is still given today.