"We will continue the fight to change this law, the public order police, the public order tribunals," she told media.
Hussein, wearing slacks was put in jail on Monday, Sep 7. She would spend one month in jail, had the fine not been paid.
"She came out of prison. We paid the 500-pound (200-dollar) fine," explained Mohiedinne Titawi, president of the Sudanese Union of Journalists.
Hussein, who resigned from her UN job as a media officer said that she was unaware as to who paid the fine.
"I don't even know who paid the fine, I had told my family and friends not to pay it," Hussein said.
Sudanese law in the conservative Muslim north states a maximum of 40 lashes for wearing indecent clothing.
Her case attracted international attention.
"Lubna Hussein's case is, in our view, emblematic of a wider pattern of ... application of discriminatory laws against women in Sudan," said Rupert Colville, spokesman for the United Nations High Commissioner for Human Rights.