Following the Clausura 2006 season in which Cabañas won his first goalscoring crown in the Mexican League, he attracted the attention of Club América, one of the most important clubs in the country, and was signed by the Mexico City squad prior to the Apertura 2006 season.
Cabañas has become América's most prolific goalscorer for 2007, finishing up the first half of the year with an impressive 19 goals between Copa Libertadores 2007 (in which he became the top-scorer with 10 goals) and the Primera División de México. He started the second half of the year with a single goal in the North American SuperLiga, then scored 4 more goals in the Copa Sudamericana 2007, and has scored 9 more in the Primera División de México, bringing his year's total with the club to 33 goals. His top form in 2007 earned him the Paraguayan Footballer of the Year and South American Footballer of the Year awards.
For 2008, Cabañas has started where he left off in 2007. He has scored 3 goals in the InterLiga 2008, scored 8 in the Copa Libertadores 2008 (in which, for a consecutive second time, he became the top-scorer), and has scored 6 more goals in the Primera División de México. He started the second half of the year with 5 goals in the Primera División de México, bringing his year's total to 22 goals so far with the club. On July 27, 2008 Cabañas makes the 2-0 score (during the first half ) yet again makes the 3-0 (during towards the end of the second half) against current champions Santos Laguna during the first match of the Apertura 2008.