This terrestrial species is found within undisturbed primary rain forest habitats, dry forests, humid to dry lowland forests, and savannas. It has been reported to survive in fragmented landscapes in the Cerrado of Brazil (Lemos et al. 2018, Ferraz et al. 2021). It excavates burrows, usually in grasslands or open areas of the forest, and is considered an ecosystem engineer (Desbiez and Kluyber 2013). The species spends 75–80% of its time underground; accelerometer data show that giant armadillos are not active and do not feed while underground, suggesting a fossorial behaviour (Desbiez et al. 2021). Habitat selection of giant armadillos seems to vary, among others, according to sex and life stage, but  forests showed to be fundamental for the survival of the species (Desbiez et al. 2020). Home range size has been estimated to be at least 452 ha (Carter 1985) in the Brazilian Pantanal. Median home-range size of adults was reported at 2,518 ha, with males occupying median ranges of 5,109 ha and females of 1,998 ha (Desbiez et al. 2020). 

The high prevalence of termites and ants identified in the faecal simples of giant armadillos confirms their myrmecophagous specialization (Teixeira Nascimento et al. 2024), even though a diverse array of invertebrates, plants, fruits, have also been found (Wallace and Painter 2013, Campos et al. 2016, Teixeira Nascimento et al. 2024).  

Male and female giant armadillos reach sexual maturity at 6.5–8 years of age (Luba et al. 2020). Reproduction seems to be aseasonal in the Pantanal of Brazil (Desbiez et al. 2020) but seasonal in the Llanos of Colombia (Aya-Cuero et al. 2015). Gestation length is 5 months, and the females usually give birth to one offspring (Desbiez et al. 2020). Parental care is long. The offspring remain inside the burrow and are completely dependent of the mother’s milk for 6–8 months. Although the weaning process ends at about 1 year of age, the offspring remain with their mother until they are 18 months old (Desbiez et al. 2020). Due to the long dependence of the offspring from their mother, the interbirth interval probably exceeds 3 years (Desbiez et al. 2020). The longevity of P. maximus is unknown, but seems to be at least 18 years (Desbiez et al. 2021).

Based on available scientific information, the generation length has been estimated at 11 years (Luba et al. 2020).

This largest of all extant armadillo species is restricted to northern and central South America, where it occurs east of the Andes. If can be found from northern Venezuela and the Guianas (French Guiana, Guyana, and Suriname), south to Paraguay and northern Argentina. 
This species has disappeared from large parts of its southern range, and possibly from other parts of its range. It may be extinct in Uruguay, and is not listed at all for this country by Fallabrino and Castiñeira (2006). It has been recorded from sea level up to 500 m asl.

Priodontes maximus is listed in Appendix I of CITES. It is present in many protected areas. 

The species is regionally extinct in Uruguay, listed as Endangered in Argentina (Di Blanco and Superina 2019) and Paraguay (Abba et al. 2017), and considered Vulnerable in eight countries; the two remaining range countries do not maintain threatened species lists (Superina and Abba 2020). In Paraguay there are very few records in the last 50 years from the Oriental region east of the Paraguay River, and the majority of the population now appears to be confined to the northern Chaco region (Smith and Ríos 2018).

Long-term research and conservation initiatives are being implemented in Brazil (Giant Armadillo Conservation Program) and Colombia (Programa de Conservación y Manejo de los Armadillos de los Llanos Orientales de Colombia). Among others, the “canastras e colmeias” initiative in Brazil promotes the peaceful coexistence between beekeepers and giant armadillos (Desbiez et al. 2020). In Colombia, the Armadillo Conservation Program is implementing different strategies to establish armadillos as flagship species in the Llanos and closely works with plantations to implement good practices that benefit armadillos (Superina et al. 2019, Superina and Trujillo 2023). In Argentina, the Proyecto Tatú Carrera aims at establishing a long-term study to understand how landscape features affect giant armadillo presence and persistence and its role in the ecosystem to promote a conservation plan for the species (Di Blanco et al. 2020, 2022).