The Chicago Teachers Union said the strike authorization received 90 percent approval, with 23,780 of its 26,502 members voting for it, the Chicago Tribune reported.
Union President Karen Lewis said the lopsided vote was "an indictment of the state of the relationship between" the Chicago Board of Education and the district's teachers.
The vote gives union leaders bargaining leverage by giving them authority to call for a strike this fall if a deal can't be reached, union officials said. An arbitrator is to issue recommendations July 16.
District officials had wanted the union to hold off on a vote until that happened.
"CTU leadership pushed their members to authorize a strike before giving them the opportunity to consider the independent fact finder's compromise report due in July," Chicago Public Schools Chief Executive Officer Jean-Claude Brizard said. "That's a shame. The CTU leadership left the teachers with a choice between a strike and nothing -- that's a false choice."
Chicago teachers haven't gone on strike since 1987, when they were out for 19 days.