Two weeks after the state elections in North Rhine-Westphalia, the Greens decided to start coalition negotiations with the CDU.
The delegates of a state party council in Essen voted on Sunday evening by show of hands for talks on a black-green coalition in the most populous federal state.
Lead candidate Mona Neubaur thanked the delegates for the "leap of faith" after more than three hours of debate.
The party has shown "that we are ready to take the next step".
According to the party council management, there were no dissenting votes in the vote.
Seven delegates abstained.
CDU and Greens had successfully completed exploratory talks on Friday evening.
The state board of the CDU in North Rhine-Westphalia also wanted to decide on the start of the coalition negotiations on Sunday.
Prime Minister Hendrik Wüst's CDU clearly won the election on May 15, with the Greens finishing third with a record result behind the SPD.
In addition to a black-green alliance, a traffic light government made up of SPD, Greens and FDP would be mathematically possible as a governing coalition.
The third option, a grand coalition of SPD and CDU, has not yet been discussed.