26-year-old Erfan Soltani was arrested at his home in early January in connection with a demonstration in the city of Fardis, west of Tehran.
Soltani was released on Saturday and has had all of his belongings returned, including his phone, according to the lawyer.
Erfan Soltani is one of thousands arrested since the protests began in late December. Shortly after his arrest, his family was reportedly told that he had been sentenced to death, a decision later reversed by Iran's chief judge.
Iran has been rocked by protests in recent weeks. Thousands of people have been killed, according to exiled organizations.
