Background and Objective: Understanding which and how instruments have been used to measure physical activity (PA) in different population groups (i.e., children, adolescents, adults, and older adults) in Brazil is a preliminary step for an effective national monitoring system. This review aimed to map the instruments of PA applied to the Brazilian population. Methods: A scoping review was conducted in July 2020 in six databases (Web of Science, MEDLINE/PubMed, LILACS, PsycInfo, Scopus, and SPORTDiscus). The selection criteria were: original articles published up to 2020 in English, Portuguese, or Spanish languages; studies that included data from the general Brazilian population using PA questionnaires. Extracted information included methodological aspects, validation, and feasibility of the instruments. Independent peers performed all processes. Data were summarized according to age group (children: <12 years-old; adolescents: 13–17 years-old; adults: 18–64 years-old; and older adults: 65+ years-old). Results: A total of 9,177 were identified, and 765 articles met the inclusion criteria. They represented 390 different studies. A total of 17 (4.3%) studies were nationwide surveys, and 47 (12%) studies included users from the national healthcare system. Thirty-eight distinct instruments were identified. The “PA Questionnaire (PAQ-C/A)” was the most frequent in children (9/33), while the “International PA Questionnaire (IPAQ)” was the most frequent in adolescents (26/81), adults (152/189), and older adults (59/85). Information on reliability and validity varied largely according to the instrument and age group. Conclusions: This review showed that a large number of distinct instruments on PA have been used in the Brazilian population, and a small part of the PA instruments has been used in the national health system. This evidence supports a call for the development and validation of instruments on PA behavior in different age groups as part of the Brazilian health system.