Objective: To determine tinnitus prevalence and severity in a cohort of unselected first-time cochlear implant (CI) recipients whose primary motive for CI was sensorineural hearing loss (SNHL), and to evaluate the effect of CI on tinnitus after cochlear implantation. Methods: Prospective longitudinal study of 45 adult CI recipients with moderate to profound SNHL. Patients completed the Danish version of the Tinnitus Handicap Inventory (THI) and a visual analogue scale (VAS) for tinnitus burden before implantation, 4 months after implantation and 14 months after implantation. Results: The study included 45 patients, of which 29 (64%) had pre-implant tinnitus. Median THI score (IQR) significantly decreased from 20 (34) to 12 (24) at first follow-up (p < 0.05) and to 6 points (17) at second follow-up (p < 0.001). Median VAS (IQR) for tinnitus burden decreased from 33 (62) to 17 (40; p = 0.228) and 12 (27, p < 0.05) at the first and second follow-ups, respectively. Tinnitus was totally suppressed in 19% of patients, improved in 48%, remained unchanged in 19% and worsened in 6%. 2 patients reported new tinnitus. At the second follow-up, 74% of patients had slight or no tinnitus handicap, 16% had mild handicaps, 6% had moderate handicaps, and 3% had severe handicaps. High pre-implant THI and VAS scores correlated with greater decrease in THI scores over time. Conclusion: 64% of the patients with SNHL had pre-implant tinnitus, which was decreased 4 and 14 months after implantation. Overall, 68% of patients with tinnitus improved their tinnitus handicap after CI. Patients with higher THI and VAS scores had a larger decline and the highest benefits in terms of tinnitus handicap improvement. The study findings demonstrate that the majority of patients with moderate to profound SNHL eligible for cochlear implantation benefit from complete or partial tinnitus suppression and improved quality of life after implantation.