Early recurrence of atrial arrhythmia (ERAA) during a blanking period after catheter ablation (CA) for atrial fibrillation (AF) does not always result in subsequent AF recurrence. We investigated whether failed electrical cardioversion (ECV) during the blanking period was associated with recurrence. A total of 1,240 consecutive patients who underwent first-time CA for AF at our institution between March 2012 and March 2016 were investigated. Among the 517 patients (42%) who experienced ERAA, 262 underwent ECV. Failure or success of ECV was defined according to the current expert consensus statement. Failed ECV was defined as failure to terminate AF and/or relapse into AF within 30 seconds after transient sinus rhythm conversion by ECV with a shock energy of 270 J in this study. Of the patients, 254 (97%) with restored sinus rhythm were included, and 8 who experienced sustained AF afterward and discontinued the rhythm-control strategy were excluded. We divided the 254 patients into the following 2 groups on the basis of failed or successful ECV: failed-ECV (n = 105; at least 1 failed ECV but experienced successful ECV at a later date nevertheless) and successful-ECV (n = 149, no failed ECV) groups. At the median follow-up period of 610 days after CA, the recurrence rate was higher in the failed-ECV group than in the successful-ECV group (76.2% vs 45.6%, log-rank p < 0.001). After adjustment for baseline differences, failed ECV was found to be a significant predictor of recurrence in the multivariate model (p < 0.001). In conclusion, failed ECV for ERAA was an independent predictor of future recurrence.