Plainclothes officers broke down the door and seized her daughter Imaan Mazari-Hazir, a lawyer and activist, Ms Mazari said on social media platform X.
"Of course no warrants or any legal procedure. State fascism," she wrote.
Her daughter is a founding partner of a law firm in Islamabad.
Early on Sunday morning, she tweeted about "unknown persons" jumping over the gate to her home and shutting down her security cameras.
Police confirmed she was arrested for "interference in state affairs, staging a sit-in and resistance", according to Pakistan's Geo TV.
The Human Rights Commission of Pakistan has condemned her arrest.
In the country's latest political standoff, Pakistan's President and PTI member Arif Alvi said on Sunday he had refused to sign into law two bills that would give authorities more power to prosecute people for acts against the state and military, a move the law ministry said was unconstitutional.
"The manner in which @ICT_Police broke into her home, allegedly without a warrant, is unacceptable and points to a larger, more worrying pattern of state-sanctioned violence against people exercising their right to freedom of expression and assembly," it said.
Her arrest comes a day after opposition leader Shah Mehmood Qureshi was detained amid disputes over the country's upcoming elections.
Mr Qureshi, twice foreign minister, was arrested at his Islamabad home only hours after he said he would launch a legal challenge to any delay of the national elections at the Supreme Court.
PTI spokesman Zulfi Bukhari said Mr Qureshi had been "arrested for doing a press conference and reaffirming PTI stance against all tyranny and pre-poll rigging that is going on currently in Pakistan".
Mr Qureshi, who has led PTI since the arrest of party chairman Imran Khan, told the press conference: "It will be unconstitutional if the 90 days deadline is breached."
Elections are due to be held by November, within 90 days of parliament's dissolution last week.
A caretaker cabinet has since been announced, led by Anwaar ul-Haq Kakar, a little-known politician said to be close to the military.
Analysts have warned Pakistan could return to military rule if the current caretaker set-up stretches beyond the 90 days.
Ms Mazari, who served as minister for human rights, resigned from politics after violence broke out over the arrest in May of Mr Khan, who was sentenced to three years in prison this month for selling state gifts.
His three-day detainment sparked deadly violence across the country and led to a crackdown on the PTI, with almost all senior leadership arrested or forced into hiding.
The popular leader has been barred from contesting an election for five years.
Violence erupted between his security forces and large crowds of his supporters on several occasions, including during several attempts to arrest him as supporters camped outside his home.
Protesters gathered outside his Lahore home following his sentencing, while others took to the streets in Peshawar, Punjab, Khyber Pakhtunkhwa and other parts of the country.
Mr Khan was found guilty of buying and selling state gifts valued at more 140 million Pakistani rupees ($635,000).
The 70-year-old has appealed the conviction. More than 180 allegations were made against him.
"The arrests of PTI workers [after] the May arrest of Imran Khan coupled with draconian laws passed in haste by [the coalition government] have had a chilling effect on Pakistani citizens," columnist Usama Khilji told AFP.
The PTI and Mr Khan's supporters say he is a victim of a "witch hunt" led by former prime minister Shehbaz Sharif.
Mr Sharif denied holding any personal grudge against Mr Khan in an interview with UK newspaper The Guardian last week.
"We were treated shabbily and the jail manual was violated when Khan was PM" he said. "We were terribly victimised. But we don’t believe in tit for tat."