Valdez formally filed for re-election to a second term on December 3, 2007. Valdez won the 2008 primary, narrowly avoiding a runoff by winning 50.85% in a four-candidate field on March 4, 2008. On November 4, 2008, Lupe Valdez was re-elected Sheriff of Dallas County with 388,327 votes to Lowell Cannaday's 322,808 votes, a margin of roughly 65,500. Valdez received over 99,000 more votes than the "Straight Democratic" option. She won in precincts across Dallas County, including formerly Republican areas including Valley Ranch in Irving and Mesquite. She began her second four-year term on January 1, 2009.