The COVID-19 pandemic altered people’s life dramatically worldwide, with major concerns in different economic, political, scientific, and public health aspects. The impact on the lifestyle behaviour of the young generation was larger than anticipated. To better understand the influential factors on the lifestyle of tertiary students in an NZ polytechnic due to the COVID-19 pandemic and their correlations, a questionnaire was administrated online by SurveyMonkey to investigate the impact of COVID-19 on life overall, study time and reasons for changing, stress level, living conditions, eating patterns, choice of food, physical activity level, social activities, and sleep time. Data were analysed using descriptive statistics, frequency, and correlations to explore the patterns of the influences and the impact of COVID-19 on the proposed questions. The results showed that the extent of the impact of COVID-19 on students’ life, in general, was 3.8 (from 0: not at all to 5: considerably). The main reasons for students who either needed an extension or time-off or changed to part-time study were increased stress level (63%), financial reasons (16%), and family responsibilities (14%). For the comparison aspects (prior vs. post-COVID-19 lockdown), meaningful differences were observed in physical activity level (3.26 vs. 2.50) (from 1: very light to 5: very active); and the importance of factors that influenced the choice of food was convenience (3.62 vs. 3.41) and nutrition value (3.65 vs. 3.50) (from 1: very less important to 5: very important). Students were anxious because of fear of infection, lacked physical exercise due to lockdown, and had trouble sleeping. The results of the study provide useful information on the impact on daily life for tertiary students in pandemic times. The research findings can inform health professionals of these influences for appropriate policy decisions and public health practices to promote a healthy lifestyle during a pandemic.