Moreno spent a year in Texas at age 12 and spent succeeding summers there before earning a scholarship for four years of college soccer at UNC Greensboro. He finished his college career fourth on the team's all-time scoring lists, with 65 goals and 25 assists, having been named first team NSCAA All-South all four years with the team.
Alejandro Moreno won 4 MLS Championships during his professional career.
After completing his career at Greensboro, Moreno was drafted 27th overall in the 2002 MLS SuperDraft by the Los Angeles Galaxy. He played sparingly in his rookie season, but developed into an excellent sparkplug coming off the bench in his second season, when he registered six goals and two assists in just 1,117 minutes.
Although Moreno exhibited a good deal of promise in 2003, he was not able to earn a consistent starting role with the Galaxy because of a logjam at the forward position, which included Guatemalan star Carlos Ruiz and former US international Jovan Kirovski, as well as recent acquisition Joseph Ngwenya. In 2004, Moreno again registered six goals and two assists, this time in 1,297 minutes. He was traded to San Jose Earthquakes in the off-season in a four-player deal. In his lone season with the Quakes, Moreno scored eight goals and four assists. Along with the rest of his Earthquakes teammates, he moved to Houston for the 2006 season.
Moreno was traded to Columbus Crew on May 10, 2007 in exchange for Joseph Ngwenya. He scored the first goal in the 2008 MLS Cup for Columbus, who eventually won the game 3-1 against New York Red Bulls.
Moreno was selected by Philadelphia Union in the 2009 MLS Expansion Draft on 25 November 2009.
On November 24, 2010, Moreno was selected by Vancouver Whitecaps FC in the 2010 MLS Expansion Draft, but was immediately traded to Chivas USA, along with Alan Gordon, in exchange for allocation money and an international roster spot.
Moreno remained with Chivas USA through the 2012 season. After the conclusion of the 2012 season, Chivas USA declined the 2013 option on Moreno's contract and he entered the 2012 MLS Re-Entry Draft. Moreno became a free agent after he went undrafted in both rounds of the draft. In February 2013 he joined the Philadelphia Union as a television commentator, ending his playing career.
Moreno's performances in MLS have seen him receive call-ups for the Venezuela national team; he made his first appearance on February 18, 2005 against Australia. Due to his high quality of form during the 2008 Major League Soccer season, Moreno was again called up to the Venezuelan team for some 2010 World Cup Qualifiers, scoring against Ecuador on October 15, 2008, in a 3-1 win.
In 2013, ESPN FC hired Moreno as a color commentator and analyst. He frequently covers Liga MX and Mexico national football team games on ESPN's English-language networks. In 2014, he served as color commentator for the Philadelphia Union of Major League Soccer.Major League Soccer MLS Cup (1): 2008
Major League Soccer Supporter's Shield (2): 2008, 2009
Major League Soccer MLS Cup (1): 2006
Major League Soccer Supporter's Shield (1): 2005
Major League Soccer MLS Cup (1): 2002
Major League Soccer Supporter's Shield (1): 2002