Jessica Diggins (born August 26, 1991) is an American cross-country skier. She is the most accomplished cross-country skier from the United States in the sport's history having won four World Cup overall titles, four Olympic medals, seven World Championship medals, and numerous other event championships. The New Yorker described Diggins as "the greatest American ever to put on a pair of skinny skis, and arguably the greatest winter endurance athlete this country has ever produced". She announced that she would retire from competitive cross-country skiing after the 2025–26 season.

Diggins and teammate Kikkan Randall won the United States' first-ever cross-country skiing gold medals with a team sprint victory at the 2018 Winter Olympics in Pyeongchang. At the 2022 Winter Olympics, Diggins won the silver medal in the 30 kilometer freestyle and the bronze medal in the individual sprint, making her the most decorated American cross-country skier of all time. At the 2026 Winter Olympics, she won a bronze medal in the 10 kilometer freestyle.

Diggins has also won seven medals, including two golds, at the FIS Nordic World Ski Championships, from 2013 to 2025. She was the first American to win an individual event gold medal by winning the 10 kilometer freestyle in 2023. Diggins has competed in the FIS Cross-Country World Cup since 2011. In 2021, she won the women's overall title for the 2020–21 FIS Cross-Country World Cup, becoming the first American woman to win a season title and the first American to win one since Bill Koch in 1982. Diggins again won FIS Cross-Country World Cup overall titles in the 2023–24, 2024–25, and 2025–26 seasons.

Diggins has used her status as a famous athlete to advance advocacy related to climate change and eating disorders.

Jessica "Jessie" Diggins was born in Saint Paul, Minnesota, to parents Clay Diggins and Deb Diggins (née Robinet). Her parents are both originally from Canada. Diggins grew up in Afton, Minnesota. She has one sister, Mackenzie. Diggins attended Stillwater Area High School, graduating in 2010.

Diggins began skiing at age four and participated in the Minnesota Youth Ski League. She showed prowess for skiing at age 11 when she started competing against older children.

Diggins competed for Stillwater Area High School's cross-country ski team. In 2008, Diggins was the top-ranked girls' individual cross-country skier in the Minnesota high school rankings. She won the Korteloppet races in 2008 and 2009 as part of the American Birkebeiner festival in Wisconsin while she was still in high school. She fell out of the Minnesota high school rankings in 2009 when she competed and won the United States Junior National Sprint title on March 9 of that year. She was added to the United States World Junior Cross-Country Ski Team in 2010.

Diggins earned an academic scholarship to Northern Michigan University but deferred enrollment to race with the Central Cross-Country Elite team for one year. She decided to race professionally rather than attend college. She was named to the United States Ski Team in 2011 and competed at her first World Championships that year.