The FANTASTIC questionnaire is a scientific instrument that can be used by health professionals for quickly and effectively measuring the quality of life and lifestyle of people. It is a simple questionnaire that measures different dimensions including nutritional status, but the possibility of using it as a resource for studies in the nutritional field (regardless of its correlation with this) has never been considered, nor has it been used for studies in university populations. The aim was to validate the FANTASTIC questionnaire to report on the participant’s lifestyle in a Spanish university population by using a cross-sectional study. A sample of 501 participants was obtained. The study was approved by the Ethics Research Committee of Catholic University of Valencia, and written informed consent was obtained from all participants. Sociodemographic, lifestyle variables, habitual diet, and nutrition-related lifestyle were collected individually. Participants also completed the self-administered FANTASTIC questionnaire. The reliability analysis of the FANTASTIC questionnaire revealed a Cronbach’s Alpha statistic result of 0.797. The Kaiser–Meyer–Olkin (KMO) value was 0.786, with a significant Bartlett’s Test of Sphericity (p = 0.000). This shows that the FANTASTIC questionnaire has good internal consistency and good construct validity. A retest was performed in four weeks’ time, showing excellent intraclass correlation values. We consider the applicability of the FANTASTIC questionnaire for nutritional studies in Spanish university students to be appropriate, and most students have high scores in the nutritional aspects of the questionnaire, showing correct diet implementation and good cooking skills.