Objective: This study assessed the ecological validity of the Yale Food Addiction Scale (YFAS 2.0) with ecological momentary assessment (EMA) and explored the internal consistency and convergent validity of a momentary food addiction scale. Method: Adults (N = 49) who met criteria for binge-eating disorder and/or food addiction (age = 34.9 +/- 12.1 years; 77.1% cisgender female; 55.1% non-Hispanic White) completed online questionnaires and a 10-day EMA protocol. Analyses examined (a) associations between the YFAS 2.0 and EMA-measured variables corresponding to food addiction criteria, (b) reliability of a momentary food addiction scale (EMA-FA), and (c) concurrent associations between EMA-FA and EMA-measured negative affect, impulsivity, eating expectancies, body satisfaction, consumption of palatable food, and taste response to palatable food. Results: YFAS scores were associated with EMA-reported variables corresponding to food addiction criteria (ps < .045). The multilevel reliability for EMA-FA was adequate (omega = .75-.94). Individuals with higher EMA-FA scores reported greater negative affect, impulsivity, appetite, palatable food consumption, taste response to palatable food, and contrary to expectations, greater body satisfaction (ps < .01). Within-person effects emerged for EMA-FA predicting higher negative affect, impulsivity, likelihood of palatable food consumption, more pleasurable taste responses after consuming palatable foods, yet lower body satisfaction, appetite, and eating expectancies (ps < .01). Conclusions: Results support the ecological validity of the YFAS 2.0, and additional evidence of convergent validity and internal consistency was demonstrated for a momentary food addiction scale. This assessment of the psychometric properties of the YFAS will ultimately further its utility and relevance in the study and diagnosis of food addiction.