Objective This study aimed to investigate correlation between 4‐hour delayed‐enhanced 3.0 Tesla (3T) 3D‐fluid‐attenuated inversion recovery (FLAIR) MR images and audio-vestibular function in idiopathic sudden sensorineural hearing loss. Setting Tertiary center Methods All patients underwent 4‐hour delayed‐enhanced 3D‐FLAIR MR imaging for identifying lesion-side laterality and enhanced labyrinth patterns. Audiologic and vestibular function tests were performed. Vestibular function test sum scores were additionally calculated by summing the scores on each test and defining normal as 0 and abnormal as 1. The hearing recovery was evaluated according to the American Academy of Otolaryngology-Head and Neck Surgery Criteria at 3 months after the end of treatment. Results Lesion-side laterality was identified in 31 (40.8%) of the 76 patients with ISSNHL and these patients had a lower hearing recovery rate (P<0.05). Furthermore, patients with a lower initial hearing threshold (dB), word recognition score, and lesion-side posterior semicircular canal gain displayed poorer hearing recovery (P<0.05). Initial hearing threshold and word recognition score did not change significantly as the extent of the enhancement in the labyrinth increased; however, the probability of being accompanied by vertigo and the total score on the vestibular function tests did increase (P<0.05). Conclusions Lesion-side laterality of the labyrinth in ISSNHL can be identified on 4-hour delayed-enhanced 3DFLAIR MR images. The extent of enhancement in the labyrinth is associated with clinical findings such as impaired audio-vestibular function, and also with the prognosis of ISSNHL. Keywords: Idiopathic sudden sensorineural hearing loss, 4-hour delayed 3D FLAIR MRI, Audiovestibular function, Prognosis. Level of Evidence; 4