Frank Engli was born in Chicago, where he also studied at the Academy of Fine Arts. After graduation, he hitchhiked through the country, taking on several odd jobs, including a stint as arti director for Western Electric in Kearny, New Jersey. He did single-panel gag cartoons for a while, before he became Bill Dwyer's letterer on 'Dumb Dora' in 1932. A year later he found a job in the animation department of the the Fleischer Studios in Manhattan. There, he worked on many cartoons with 'Popeye' and 'Betty Boop'. From 1934 he worked as a letterer and colorist on the comics by Milton Caniff and Noel Sickles, including 'Terry and the Pirates', 'Male Call', 'Steve Canyon' and 'Scorchy Smith'. He stayed with Caniff until his retirement in 1977.
In addition to his lettering work, he created his own strip in 1940, 'Rocky, the Stone Age Kid', for Comic Book Magazine, which was published by the Chicago Tribune. In 1946 and 1947, he drew 'Looking Back', a strip distributed by Field Enterprises. He also did occasional work for Harvey Comics.