Moseley was born in the Capital City of Puerto Rico. In 1978, Moseley saw snow for the first time when his family went on a trip to California. Eventually, his family moved to Tiburon, California, a suburb north of San Francisco. His family would always go to the Sierra Nevadas every weekend. This plus this fact that he was better than his brothers in skiing, inspired 9 year old Moseley to take skiing lessons. In 1982, he joined the Squaw Valley Freestyle Ski Team and began training in the sport he grew to love. Soon after he won his first Junior National title in Freestyle Skiing. Moseley always made time for both his school work and his training. He graduated from high school in 1993 and that same year was selected and became a member of the U.S. Ski Team.
Moseley tried but did not qualify for the 1994 Winter Olympics held at Lillehammer, Norway. He was determined to qualify for the 1998 Olympics and continued his training. In 1995, Moseley enrolled in the University of California but, his education was interrupted by his intense training and it wouldn't be until the year 2000 that he would resume his studies. The following year, he won his first World Cup Mogul.
In 1998, Moseley participated and won the first two World Cup events of the year; this led to his participation in the 1998 Winter Olympics held in Nagano, Japan where he won a gold medal. Later that year he secured the 1998 World Cup Mogul Skiing title with nine wins that season. He also won the U.S. National title.
In 2000, Moseley won the U.S. Freeskiing Open and in 2001 regained a spot in the U.S. Ski Team at the World Cup qualifications held at Sunday River, Maine. In 2002, Moseley competed but came in fourth place in the Olympic Games.
Among the honors and recognitions which Jonny Moseley has received are a parade in his honor where San Francisco Mayor Willie Brown declared a "Jonny Moseley Day" and handed him the "Key" to the city. He was named "Sportsman of the Year" (1998) by the U.S. Olympic Committee and has been featured on the cover of Freeskier and Rolling Stone magazines.
Moseley launched a web site which sells products with his logo on them and has appeared on Ads for McDonalds, Sprint and Budweiser. Playstation 2 has a game in the market called Jonny Moseley Mad Trix.
Moseley, who currently lives in California, was the host of the MTV reality show "The Battle of the Sexes".