Guillermo Franco joined the Fire from Liga MX side Pachuca where he made 12 appearances in 2012. The Corrientes, Argentina product began his career with Argentine Primera División side San Lorenzo in 1995. Franco spent the next seven seasons with San Lorenzo, scoring 23 goals in 96 matches.
In 2002 Franco joined Mexican side Monterrey, where he made 119 appearances and scored 63 goals. While with los Rayados, Franco led the team to the 2003 Clausura title and led the league in scoring during the 2004 Apertura season with 15 goals. Franco then headed to Spain where he spent the 2006-09 season with Villarreal, where he made 81 appearances and scored 14 goals, including the goal in a 1-0 victory against Celta de Vigo that sent Villarreal into the UEFA Cup.
Franco signed with West Ham United for the 2009 season where he scored five goals in 23 appearances. He then joined Argentinean side Vélez Sársfield in 2011 where he made 18 appearances and scored five goals.
Franco became a naturalized Mexican citizen in 2004 and made his national team debut in 2005. Franco scored eight times in 25 appearances for El Tri, and represented Mexico in both the 2006 and 2010 FIFA World Cups.
Franco is the fourth player on the Fire roster with FIFA World Cup experience.