Recently, combined quantitative and qualitative analysis has become popular for research. In studying careers, subjective and objective information are ideal for assessing individual career development and are relevant in career counseling. This paper measures career adaptability by combining text mining and item response theory (IRT), with college students’ self-reported career adaptability as a subjective measure and responses to questionnaire items as an objective measure. The two are combined under a Bayesian framework. Additionally, the validity of text categorization and IRT, combined with model measurement, were explored; text categorization results were used as prior information when estimating IRT capability parameters to test whether adding prior information can improve accuracy. This study draws the following conclusions: (1) The text classification method had the highest sensitivity in 300-person samples; however, the text-IRT method had the best predictive effect, high reliability, and unique advantages in accuracy. (2) In 600-person samples, the text classification method had the best predictive effect. The effect was relatively good, with unique advantages in identifying low career adaptability. However, this must be selected according to actual needs. If the accuracy requirement is high and sensitivity can be sacrificed, the text-IRT method is more appropriate. (3) The text-IRT method is more suitable for 900 subjects when accuracy, sensitivity, and specificity need to be considered, and text classification is best when identifying low career adaptability. (4) Sample size influenced accuracy, specificity, and the negative predictive values of text classification, as well as the sensitivity of IRT and text-IRT methods.