The family of the Asteraceae is the most diverse in the Chilean flora; nevertheless, only some tribes have undergone a recent systematic treatment, while the knowledge about the geographical distribution of the taxa is still very incomplete. From the review of herbarium specimens and fieldwork, a survey of the Compositae flora of the Arica y Parinacota Region was performed. The study shows the presence of 144 taxa of the Asteraceae family in the region of which 82.6% is native (119) and 9% is endemic to Chile (13), while 8.3% are considered as exotic species (12). The genus Senecio is the one showing the highest diversity in the region, with the presence of 27 species, including six endemic ones. The revision of the botanical material reveals the presence of five new species for the Chilean flora: Achyrocline ramosissima Britton, Gamochaeta humilis Wedd., Mniodes kunthiana (DC.) S.E. Freire et al. (=Lucilia violacea Wedd.), Pseudogynoxys cordifolia (Cass.) Cabrera, and Senecio evacoides Sch. Bip. A new species has been recently described based on our recent field surveys: Pseudognaphalium munoziae N. Bayón, C. Monti & S.E. Freire. Additionally, the correct denomination of the endemic species Stevia philippiana has been recently undertaken. The greatest diversity of species is found in the province of Parinacota, above 3,000 m asl. Compositae stand out in the region not only for its diversity but also as a crucial element of the vegetation, being a fundamental component of the precordillera and altiplano vegetation belts, known as “tolar”, in which species pertaining to genera like Parastrephia, Lophopappus, Baccharis, or Senecio tend to dominate. Indeed, most of the vegetation belts described in the Parinacota province show members of the Asteraceae as dominant species. In spite of a big amount of the regional surface under formal protection, several species occur outside the protection units.