In 1997, at the age of 15, the striker/midfielder joined the United States Youth Development Program, subsequently moving to the IMG Soccer Academy in 1999. Later that year, he signed a youth contract with Bundesliga side Bayer Leverkusen. He eventually signed a senior contract with the German club lasting from 2001 to 2005, but never settled in, leading to criticism that Donovan was too soft for European competition. He spent the majority of his contract years on loan in the US, first to the San Jose Earthquakes (2001-04), then to the Los Angeles Galaxy (2005-current).
After starring for the US national team youth sides, Donovan debuted for the senior side on 25 October 2000 in a friendly against Mexico, scoring the opening goal in the 2-0 win. He displayed impressive form in the Americans' run to the quarterfinals in the 2002 World Cup, being named the tournament's best young player.
Donovan has enjoyed record-setting success with the national team. On 11 April 2006, Donovan notched his 23rd assist in a 1-1 friendly with Jamaica, moving him past Cobi Jones as the US assist leader. And on 19 January 2008, he scored with a penalty kick against Sweden to pass Eric Wynalda as the national team's highest goalscorer on his way to his current tally of 42 goals in 120 appearances, the most caps of any active US international.