The Republican presidential hopeful says some joined the military and went to war, others went into law enforcement.
He says in the face of "overwhelming evil," America responded with love for those affected but also with "a determination to strike back against those who committed these acts."
Perry laid a wreath before an Austin, Texas monument honoring those who died 10 years ago Sunday.
He also saluted the death of Osama Bin Laden, saying "the mastermind behind these attacks has paid the ultimate price."
Perry often chides President Obama, but has publicly cheered his administration for finding and killing Bin Laden.
