According to Official Guinness Records,
The longest main sponsorship of a sporting world championship is 25 years and was achieved by Škoda Auto a.s. (Czech Republic) in Cologne, Germany, as verified on 19 May 2017. The Ice Hockey World Championships, that Škoda Auto a.s. has been sponsoring, is an annual international men's ice hockey tournament organized by the International Ice Hockey Federation (IIHF).
For a complete list of 2017 records, please visit 2017 Guinness Records in Germany.