James Younghusband's career began when he signed for Chelsea in 1997 and signed a scholarship with them at the age of 10. While with Chelsea, he made a number of appearances for the youth and reserve team. Subsequently, he also had brief stay with other English football teams in the past years. After his contract with Chelsea expired in 2008, he moved to the Philippines.
On 15 April 2011, it was reported that Younghusband and his younger brother Phil, announced that they will join San Beda for the 2011 National Club Championships under former national coach Aris Caslib. In the final, San Beda lost 3–0 to Teknika in the first leg. In the second leg, Younghusband scored from a free kick to make the score 2–0 to San Beda. San Beda, however, were not able to find a third a goal and Teknika won 3–2 on aggregate.
After the conclusion of the 2011 National Club Championship, he and his younger brother would be joining Loyola Agila on three-year deals.
In a round of 16 match in the 2011–12 United Football Cup match, Younghusband scored his first goal for Loyola in a 14–0 win over Sunken Garden United. He scored his second goal in the semi-finals in a 5–4 victory over Kaya after being 3–0 down at half-time. Loyola lost the final 2–0 to Philippine Air Force.
Younghusband scored his first league goal for Loyola in a 2–1 victory over Philippine Army. He then scored a brace in a 4–3 win against Global before adding another against Kaya. He then scored a hat-trick in a 14–0 thrashing of Philippine Navy. Leading 3–1, Younghusband received his first red card in the United Football League after a row with Air Force player Herbert Bayona after which Younghusband shoved Bayona. The sending off inspired Air Force to score twice in one minute to draw the match 3–3.
Early in 2005, the Philippine Football Federation was alerted to Younghusband's eligibility by a mysterious gamer who allegedly found out about their lineage via the Football Manager series. He and his younger brother Phil were eventually called up to the Southeast Asian nation's football squad, amidst much fanfare. Younghusband participated in the 2005 Southeast Asian Games, which was held in the Philippines. He also ensured the advancement of the Philippine team to the group stage of the 2012 AFC Challenge Cup qualification by scoring in the 4th minute of the away match against Mongolia in the qualifying play-off.
James Younghusband missed the final cut of the Azkals' lineup ahead of the team's match against Bahrain, leaving Phil to carry the squad on June 11 at the Philippine Sports Stadium in Bulacan. Coach Thomas Dooley said his decision was nothing personal against the midfielder, and that he was only concerned about building the roster from his best-performing players.
"It's performance that counts. It's not who you are, it's not how old you are, how famous you are," said Coach Dooley in an interview. "You need to work hard in training to get your chance to play in the game."Scores and results list the Philippines' goal tally first.
Younghusband was born in Ashford, Surrey, England to a British father and a Filipina mother (both deceased). He is the brother of Philippine team forward Phil Younghusband.