The Switzerland winger could not agree terms over a new deal with the Bundesliga outfit and will now seek pastures new after seven years at the BayArena
The 27-year-old's contract was due to expire on June 30, and sporting director Rudi Voller claimed in May that a decision would be made regarding the Switzerland international's future in due course.
However, only a few days after Leverkusen went public with their admission, a surprised Barnetta hit back: "Nothing has been decided. Neither me nor my advisor have spoken to the club."
Nonetheless, negotiations between both parties have now ground to a halt, and Barnetta will look for a new club this summer, with interest from Spain, England, France and Italy reportedly hotting up.
The winger joined Leverkusen in 2004 from St Gallen and went on to make 180 Bundesliga appearances for the side, scoring 32 times, but saw himself fall out of favour after an injury-laden 2011-12 campaign.