Donald Young, Jr. started playing tennis at the age of 3 with his father, Donald, Sr., and mother, Illona. Young’s parents have continued to coach him during his professional career. Young was 10 years old when he became the nation’s No. 1 ranked junior in the 12-and-Under Division. That same year, Young was a ball boy for a senior event in Chicago attended by John McEnroe. McEnroe agreed to exchange shots with Young and was surprised by his fluency and focus. “He has hands like another lefty I know very well,” McEnroe said. McEnroe monitored Young’s progress and encouraged IMG, his agency, to sign him.

In 2004, Young began his professional career. Despite his age, he moved about the court with the sureness and savvy of a more seasoned player. The following year, he won the Australian Open boys’ singles title and the US Open boys’ doubles title with Alex Clayton. At 16 in 2005, he became the first and youngest Black player to end the year ranked No. 1 in the world among juniors. Young claimed the Wimbledon boys’ singles title in 2007.

In his professional career, Young reached career-high rankings of No. 38 in singles in February 2012 and No. 43 in doubles in August 2017. He won nine Futures and Challenger titles. Young has competed in all four Grand Slam tournaments. His best Grand Slam singles results were at the 2011 and 2015 US Opens. In 2011, Young reached the Round of 16 where he faced Andy Murray. In 2015, Young reached the Round of 16 again, where he lost to Stan Wawrinka. Young’s best Grand Slam doubles performance was at French Open in 2017. There, he and his partner Santiago Gonzalez reached the final. Although ultimately defeated by Ryan Harrison and Michael Venus, Young and Gonzalez defeated several high-ranking opponents in the previous rounds, including Jamie Murray and Bruno Soares. In 2024, he reached the US Open mixed doubles final alongside fellow boundary breaker Taylor Townsend. Young retired from professional tennis after the 2024 US Open.