Introduction: Internationally, one of the most widely used instruments for assessing romantic attachment is the Experiences in Close Relationships Scale (ECR), which has been validated for use in various countries. However, there is no known study of the psychometric properties of the brief version of this scale in the Ecuadorian context. The objective of the present study was to evaluate the factor structure and invariance of the Experiences in Close Relationships questionnaire, as well as its reliability in terms of internal consistency within the Ecuadorian context. Methodology: An instrumental and psychometric design was employed, assessing a sample of 710 emerging adults (68.3% female), aged between 18 and 29 years (M = 21.13; SD = 2.94). Results: Through confirmatory factor analysis, it was identified that the bidimensional structure of the brief version of the ECR replicates satisfactorily in the Ecuadorian context. Two models were tested: one with 12 items and another with 11 items, with the latter showing better fit. Furthermore, the measurement model was partially invariant between men and women. In terms of internal consistency, both dimensions (anxiety and avoidance in attachment) exhibited values greater than .90 for both Cronbach’s Alpha and McDonald’s Omega. Conclusion: Given the strong psychometric properties of the brief version of the ECR, it can be utilized by researchers and clinical professionals as a brief measure of romantic attachment in emerging adults in Ecuador.