The aim of this research is to determine the changes in pre-service teachers’ views of 21st century skills to be acquired by students before and after the pandemic, through mobile technologies. English and Social Science pre-service teachers are the samples of the research. In the research, longitudinal survey study, which is one of the quantitative research methods, was used. In the research, an open-ended question, which was asked through the mobile application called Tricider, was used as a data collection tool. The data obtained were analyzed by descriptive analysis method. In the research results, pre- pandemic and post-pandemic pre-service teachers’ opinions were raised about access to information in the field of “Information, Media and Communication Skills”, there was a change in creativity from critical to critical thinking in the field of “Learning and Innovation Skills” and increasing from adaptation and entrepreneurship to “Life and Career Skills” trends have been observed. In addition, it was determined that the frequency of voting increases after the pandemic. It is recommended that pre-service teachers who will educate 21st century students focus on skills related to the field of “Information, Media and Communication Skills”, to investigate the reasons for their absences in using mobile technologies, to investigate the effectiveness of applied training in the field of “Learning and Innovation Skills” and to conduct comparative research for pre-service teachers in different branches