Luke made his film debut in "The Painted Veil" (1934), and the following year gained his first big role, as Charlie Chan's eldest son, Lee Chan, in "Charlie Chan in Paris" (1935). He worked so well with Warner Oland, the actor playing Chan, that "Number One Son" became a regular character in the series, alternately helping and distracting 'Pop' Chan in each of his murder cases. Regardless, Lee is depicted as an enthusiastic American youth of some accomplishment, including becoming an Olympic Gold Medalist in 100-metre swimming in "Charlie Chan at the Olympics" (1937). Luke appeared seven times as Lee Chan opposite Oland's Chan. Keye Luke left the Charlie Chan series in 1938, shortly after Oland died. The unfinished Oland-Luke film "Charlie Chan at the Ringside" was completed as "Mr. Moto's Gamble" (1938), with Luke now opposite Peter Lorre.