The story begins at the Portland Knitting Company, founded in 1910 by Carl Christian Jantzen and the Zehntbauer brothers. Asked to make warm rowing trunks for a Portland rowing-club member, they developed the elastic rib-stitch fabric that became the prototype for the 1915 swimsuit. The brand name eventually replaced the company's own.
The Diving Girl — designed by Frank and Florenz Clark — first appeared in advertising in 1920 and on suits in 1923, becoming one of the longest-lived apparel icons in the world; by 1932 Jantzen was reportedly the seventh best-known trademark on earth. Ownership later passed through Blue Bell, VF Corporation and Perry Ellis International, and in 2019 to Jantzen Brands Corporation.