Jeremy Wariner attended Lamar High School in Arlington, Texas, participating in multiple sports and being recognized for his outstanding speed.

Somewhat hampered by injuries late in his freshman year, Wariner regained form as a sophomore, winning both the 2004 NCAA Division I indoor and outdoor 400 metres titles.

Later that year, he claimed the national 400 m title at the USATF Championships making him the favorite for the gold medal at the 2004 Summer Olympics in Athens.

Following his Olympic successes, he turned professional, forgoing the rest of his collegiate eligibility, though he remained at his parents' house and continued to be coached by Clyde Hart.

Together with Asafa Powell (100 m) and Sanya Richards (women's 400 m) he won his sixth out of six Golden League events (400 m) in the same season, which earned him a total of $250,000.

In 2007 he filled a summer with dominating 400 m performances culminating with the Osaka World Championships where on August 31, 2007 he would win the 400 m in 43.45 s thereby improving his personal best to become the then-third-fastest of all time (only Michael Johnson and Butch Reynolds had run faster).

Wariner stated that he needed a change as Hart was nearing retirement, although the coach said that the split was due to a pay dispute.

This led to much anticipation that he could beat Michael Johnson's world record in the final, but instead he took the silver, losing to LaShawn Merritt by nearly a second.

David Neville came in third completing a United States sweep of the 400 m. Following his disappointment with the silver medal at the Olympics, Wariner admitted he had made a mistake in sacking Hart.

Outside of their personal careers, the Wariners own a Jimmy John's franchise in Dallas, Texas, where Jeremy also serves as general manager.

[16][17] In July 2023, he moved to Liberty Christian School (Argyle, Texas) to be their head track and cross country coach, along with becoming their sports information and media coordinator.