Introduction: Specialist tinnitus services are in high demand as a result of the negative effect tinnitus may have on quality of life. Additional low cost and clinically effective tinnitus management routes are imperative. One such route is providing Cognitive Behavioral Therapy for tinnitus via the Internet (iCBT). The aim of the project was to develop and evaluate the Internet-based guided iCBT for adults with tinnitus distress in the UK. Methods: An iCBT program was developed and evaluated in terms of suitability, functionality and feasibility. Further, a three-phase outcome evaluation was implemented, which included: (1) pilot single group open trial (n=37); (2) an efficacy randomized controlled trial (n=146); (3) and an effectiveness randomized controlled trial (n=92). Results: Feasibility was established in terms of recruitment potential and suitable attrition and compliance rates. All the three outcome studies showed favourable results for iCBT as a tinnitus treatment. Undertaking iCBT led to a significant reduction in tinnitus distress (medium effect size), insomnia, anxiety, depression, hyperacusis, cognitive failures and increasing life satisfaction. These results remained stable two months and one-year post-treatment. Conclusions: Guided iCBT for tinnitus using Audiological support was effective in reducing tinnitus distress and associated symptoms, especially in those with higher tinnitus severity scores.