Harry Whitney had racing operations at Newmarket in England and in his native United States. He brought Johren as a yearling to his Brookdale Farm in Lincroft, New Jersey where his race training was overseen by head trainer, James G. Rowe, Sr.
Johren was not sufficiently developed to race at age two and started his three-year-old racing season with nine straight losses before finally getting a win. In the pre-U.S. Triple Crown era, he was not entered in the 1918 Kentucky Derby, instead, his handlers chose to run stablemate, Vindex. Entered in the Preakness Stakes, Johren ran fourth but then won the Belmont Stakes, defeating Preakness winner, War Cloud. By the summer of 1918, the colt had become one of the dominant horses in American racing, winning a number of other important races including the 1918 Latonia Derby in which he defeated Kentucky Derby winner Exterminator. Johren's 1918 performances earned him Horse of the Year honors.