For translator Kathleen Ross, Facundo is "one of the foundational works of Spanish American literary history". It has been enormously influential in setting out a "blueprint for modernization", with its practical message enhanced by a "tremendous beauty and passion". However, according to literary critic González Echevarría it is not only a powerful founding text but "the first Latin American classic, and the most important book written about Latin America by a Latin American in any discipline or genre". The book's political influence can be seen in Sarmiento’s eventual rise to power. He became president of Argentina in 1868 and was finally able to apply his theories to ensure that his nation achieved civilization. Although Sarmiento wrote several books, he viewed Facundo as authorizing his political views.
According to Sorensen, "early readers of Facundo were deeply influenced by the struggles that preceded and followed Rosas's dictatorship, and their views sprang from their relationship to the strife for interpretive and political hegemony". González Echevarría notes that Facundo provided the impetus for other writers to examine dictatorship in Latin America, and contends that it is still read today because Sarmiento created "a voice for modern Latin American authors". The reason for this, according to González Echevarría, is that "Latin American authors struggle with its legacy, rewriting Facundo in their works even as they try to untangle themselves from its discourse". Subsequent dictator novels, such as El Señor Presidente by Miguel Ángel Asturias and The Feast of the Goat by Mario Vargas Llosa, drew upon its ideas, and a knowledge of Facundo enhances the reader’s understanding of these later books.
One irony of the impact of Sarmiento's essay genre and fictional literature is that, according to González Echevarría, the gaucho has become "an object of nostalgia, a lost origin around which to build a national mythology". While Sarmiento was trying to eliminate the gaucho, he also transformed him into a "national symbol". González Echevarría further argues that Juan Facundo Quiroga also continues to exist, since he represents "our unresolved struggle between good and evil and our lives' inexorable drive toward death". According to translator Kathleen Ross, "Facundo continues to inspire controversy and debate because it contributes to national myths of modernization, anti-populism, and racist ideology".