A product of CSD Municipal's youth academy, Ruiz has played for five MLS clubs (Los Angeles Galaxy, FC Dallas, Toronto FC, Philadelphia Union, and D.C.
United), scoring 88 goals in 182 MLS regular-season matches and 16 goals in the post-season, which is the record for the most post-season goals in MLS history.
In 2002, he was named the MLS's Most Valuable Player of the season.
He was a member of the Guatemalan national team from 1998 to 2016.
He is regarded to be the greatest Guatemalan player of all time.
He served as the national team captain, is the player with most caps, and is the all-time top scorer.
He played in five World Cup qualification competitions, and in September 2016 he became the all-time top scorer in World Cup qualifiers, with 39 goals.