Moreno was born in
Santa Cruz de la Sierra, Bolivia. He began his career attending the prestigious
Tahuichi Academy and playing for
Blooming from 1991 to 1994. He signed with the Colombian side
Independiente Santa Fe in 1994, but made only five league appearances for the team. In 1994 Moreno signed with
Middlesbrough, and the following season he became the first Bolivian to play in the
English Premiership. Moreno started in Middlesbrough's official opening of their new
Riverside Stadium in a friendly against Italian side
Sampdoria. He spent two years there, mostly coming off the bench. In total he made 20 league appearances for Boro, but only scored one league goal against
Barnsley, also scoring another goal against
A.C. Cesena in the
Anglo-Italian Cup. In 1996, in the middle of the
Major League Soccer season, he was signed by the league and allocated to
D.C. United, and helped lead them to the
MLS Cup. He was one of the league's best players in 1997, when he
led the league in goals (16), was named to the
MLS Best XI and won another MLS Cup for his side (he would add a third Cup and another Best XI in 1999). After the 1997 season, he spent a few games on loan back to Middlesbrough, scoring once against Stoke City. 1998 was Moreno's best season, as he scored 16 goals and added 11 assists, only losing the
MLS MVP Award to teammate and fellow Bolivian
Marco Etcheverry. He continued to play well amid constant concerns about his weight, but injuries began to take toll in 2001. He missed a large chunk of the 2002 season, and a conflict with head coach
Ray Hudson led to Moreno being traded to the
MetroStars after that season. in 2008 Moreno missed most of his one season with the Metrostars, but did score two goals, one against United. He was shipped back to United before the 2004 season and, undertaking a strict training regimen to avoid injuries, regained much of his old form. He was a finalist for MLS MVP, was named to the league's Best XI for the second time, and led D.C. to their fourth MLS Cup. He was named to another Best XI in 2005. He was named to the
MLS All-Time Best XI after the 2005 season. In 2007, he scored his 108th goal on a penalty kick against Toronto FC on 19 May, tying him with
Jason Kreis as the all-time leading scorer in MLS. Moreno and
Steve Ralston are the only players to have played in each of the first 15 MLS seasons. On 12 August 2010, Jaime Moreno and D.C. United announced that the 2010 season would be his last year with the club. His last game was at home against Toronto FC on 23 October 2010, where he scored on a penalty kick. After the
2010 MLS season D.C. United declined Moreno's contract option and he elected to participate in the
2010 MLS Re-Entry Draft. When he was not selected, Moreno retired as a player and was hired as Youth Academy Technical Training Coach for
D.C. United on 4 March 2011. ==International career==