His career started as a designer and cartoonist in 1939, publishing caricatures and editorial cartoons in newspapers. 1949 brought his debut in the film industry with "Punguţa cu doi bani" (Bag with two coins). Since 1950 he started working for Cinematographic Studio Bucharest in the animation department, that later broke into a separate animation studio, Animafilm. His most known cartoon character is a little black and white man sometimes referred to as "Gopo's Little Man" after his creator. Later in his life Popescu-Gopo confessed that he tried to start an "anti-Disney rebellion". Unable to surpass Disney's animation characters in color and beauty, Popescu-Gopo tried to be more profound in message and substance and simplify the form and techniques used. Unlike Disney's cartoon characters, Popescu-Gopo's cartoon characters were black and white, designed in simple lines.
His film "Scurtă Istorie" (A Brief History) won the Short Film Palme d'Or for best short film at Cannes Festival in 1957. The worldwide success achieved by A Brief History turned The Little Man into an iconic character, symbolizing the human race in its quest for knowledge and beauty. Ion Popescu-Gopo was to use it in another seven films. In many situations, The Little Man is shown holding a flower to his heart, which is taken to symbolize the humans' capacity and need for love.
The Gopo Awards are the national Romanian film awards. They are presented by the Association for Romanian Film Promotion and were established in 2007, celebrating the 50th anniversary of Gopo's Palme d'Or. The trophy is a sculpture by Romanian artist Adrian Ilfoveanu representing Gopo's Little Man.