The rapid advancement of information technology requires us to always keep abreast of the times in the current global era, the ease of information from various technologies, especially internet technology in internet access services so that it directly facilitates information about fast fashion products that provide many advantages and convenience in following the latest fashion trends. especially youth fashion among students as part of self-existentialization efforts, thus making them behave consumptively. The aims of this study are (1) to find out the latest technology in fast fashion (2) to find out what factors influence students' consumption behavior towards fast fashion. In this study, the population was UNY students, with a sample size of 382 students who were taken randomly. This type of research is descriptive with a quantitative approach. This research took place from February 2021 - June 2021. The measuring instrument used was a questionnaire in the form of a questionnaire with statements consisting of fast fashion consumption behavior. Questionnaires were distributed to respondents online. The results of the study show that (1) internet technology through social media significantly influences buying decisions for fast fashion products. (2) consumer behavior based on the theory of planned behavior in terms of Attitude Toward Behavior, Subjective Norm, Perceived behavior control on average, female undergraduate students of the Faculty of Engineering, who are between the ages of 20 have a higher tendency to consume fast fashion products. The measuring instrument used was a questionnaire in the form of a questionnaire with statements consisting of fast fashion consumption behavior. Questionnaires were distributed to respondents online. The results of the study show that (1) internet technology through social media significantly influences buying decisions for fast fashion products. (2) consumer behavior based on the theory of planned behavior in terms of Attitude Toward Behavior, Subjective Norm, Perceived behavior control on average, female undergraduate students of the Faculty of Engineering, who are between the ages of 20 have a higher tendency to consume fast fashion products. The measuring instrument used was a questionnaire in the form of a questionnaire with statements consisting of fast fashion consumption behavior. Questionnaires were distributed to respondents online. The results of the study show that (1) internet technology through social media significantly influences buying decisions for fast fashion products. (2) consumer behavior based on the theory of planned behavior in terms of Attitude Toward Behavior, Subjective Norm, Perceived behavior control on average, female undergraduate students of the Faculty of Engineering, who are between the ages of 20 have a higher tendency to consume fast fashion products. The results of the study show that (1) internet technology through social media significantly influences buying decisions for fast fashion products. (2) consumer behavior based on the theory of planned behavior in terms of Attitude Toward Behavior, Subjective Norm, Perceived behavior control on average, female undergraduate students of the Faculty of Engineering, who are between the ages of 20 have a higher tendency to consume fast fashion products. The results of the study show that (1) internet technology through social media significantly influences buying decisions for fast fashion products. (2) consumer behavior based on the theory of planned behavior in terms of Attitude Toward Behavior, Subjective Norm, Perceived behavior control on average, female undergraduate students of the Faculty of Engineering, who are between the ages of 20 have a higher tendency to consume fast fashion products. [ABSTRACT FROM AUTHOR]