Bhutto, who leads the Pakistan People's Party (PPP) is expected to be greeted by hundreds of thousands of supporters after she arrives at Karachi, following eight years of self-imposed exile.
Speaking at a news conference in Dubai on Wednesday, she confirmed her intention to run in the parliamentary elections slated for January next year.
The 54-year-old, who has been out of power since 1996, has rejected President Gen. Pervez Musharraf's request that she delay her return to the country.
She told the news conference that she had received threats from militants, but said: "Muslims know that if they attack a woman they will burn in hell."
Bhutto served as prime minister of Pakistan on two separate occasions, but both her governments were brought down amid corruption allegations.
President Musharraf has declared an amnesty for Bhutto to protect her against the corruption charges, but the Pakistani Supreme Court is set to hear appeals against the amnesty.
Bhutto told journalists she believed the court would leave the amnesty in place, and dismissed the allegations as politically motivated.
