Hamdi Alqudsi has been found guilty of planning a series of attacks as leader of a Sydney terrorist organisation known as the Shura in 2014.
The verdict was handed down on Thursday by a NSW Supreme Court jury.
Alqudsi knowingly directed the activities of the Shura from August to December 2014.
His plans included attacks on the Sydney Gay and Lesbian Mardi Gras, the Garden Island Naval Base in the Sydney suburb of Woolloomooloo, a courthouse, and a targeted strike on the Australian Federal Police.
The Shura, which means consultative council or consultation council in Arabic, was formed in 2013. Its initial intention was to send fighters from Australia to Syria in the war against government or coalition forces.
After these aims were disrupted by the AFP and NSW Police, the group then shifted focus to domestic terrorist activity.
Alqudsi was the leader of the group, positioning himself as "commander of the boys" and "emir of the Shura" and holding meetings at his homes in Revesby and St Helens Park, Sydney.
He, along with many Shura members, pledged allegiance to Islamic State in a ceremony at Wattamolla Beach on August 31, 2014. IS accepted this pledge around two weeks later.
In denying the Crown's case, Alqudsi claimed he had no involvement with the Shura and only met its members for social occasions. He denied responsibility for the conduct of individuals within the organisation.
Alqudsi is in custody and will be sentenced over two days starting on October 31.