Game activity as one of the effective teaching methods plays an important role in the formation of key competencies of primary school students. The article identifies and systematizes the peculiarities of the development of key competencies of primary school students through the use of game activities in physical education lessons. The competence-based approach to the implementation of the key reform of schooling «New Ukrainian School» through the formation of key competencies is indicated: communication in the state language; communication in foreign languages; mathematical competence; basic competencies in natural sciences and technologies; information and digital competence; lifelong learning skills; initiative and entrepreneurship; social and civic competence; cultural awareness and expression; environmental literacy and healthy lifestyle. Different approaches to the formation of key competencies of junior schoolchildren in physical education lessons through game activities are revealed. The game competence is characterized as the ability of a child to understand, create and participate in various games, which includes physical activity, joint interaction with peers, development of strategic and tactical thinking during the game, as well as the ability to follow the rules of the game and sports ethics. Further elaboration of the problem of developing students' key competencies through game activities is emphasized.