Pakistanis around the world and Kashmiris on both sides of the Line of Control (LoC) observed "Black Day" on Sunday "to reject India's illegal occupation of Kashmir" on October 27, 1947.
A complete shutdown was observed in occupied Kashmir, said Radio Pakistan.
Prime Minister Imran Khan in a recorded statement, aired on Sunday, assured the Kashmiri people that "all of Pakistan is standing by you".
Addressing the Kashmiri people, he said the purpose of his address was to convey a message to them that Prime Minister Imran was their counsel and their spokesperson.
He said that the United Nations had already recognised their right of self-determination and that he would continue his struggle until Kashmiris get their rights.
The premier reiterated that those talking about military support or "jihad" in occupied Kashmir are enemies to Pakistan as well as Kashmiri people.
Addressing the nation, the premier said that the Indian government has stationed 900,000 army personnel in occupied Kashmir to terrorise people. "This is their [the Indian government's] objective," he said.
The prime minister said that the Indian government is looking for excuses to unleash military power on the Kashmiri people. He added that the Indian government wants to stage a Pulwama-style incident.
"The Modi government wants to hold Pakistan responsible [for unrest in Kashmir] and hide from the world what they are doing in Kashmir," he said.
Prime Minister Imran said that the Modi government wants to crush the Kashmiri people and subject them to cruelty while using this [any military support from Pakistan] as a justification.
"It is a political struggle," he reminded the nation.
Frustration, anger and fear have been growing in the region since August 5, when the Indian government stripped occupied Kashmir of its semi-autonomous status and imposed a curfew and a communications blackout. With a brief restoration in some call and text services for mobile phone services, the clampdown has now continued for over 80 days.
Black Day observed
Earlier in the day, the premier in a statement on Twitter had said this Kashmir Black Day is distinct from other years, Radio Pakistan reported.
He had said that on Oct 27, 1947, India had illegally occupied Jammu and Kashmir and on Aug 5 of this year, "it took further steps to unilaterally alter the disputed status of the territory and change its demographic structure and identity".
Through the deployment of additional troops and the "unprecedented media and communications blackout", occupied Kashmir had been turned into the "largest prison on the planet", added the premier.
Prime Minister Imran said that Pakistan demands the "immediate lifting of the curfew and communications blackout as well as rescinding of India's illegal and unilateral actions in the occupied territory".
In his message, President Dr Arif Alvi said: "Indian occupying forces are perpetrating unspeakable crimes against Kashmiri people, including women and children, with complete impunity."
Foreign Minister Shah Mahmood Qurershi assured Kashmiris "that not only do we commemorate their exemplary grit and spirit on the occasion of Kashmir Black Day" but also "reiterate our firm and continued political, moral and diplomatic support to the people of IOJ&K in their grand struggle until they achieve their legitimate right of self-determination as per the United Nations Security Council resolutions".
"India should realise it cannot fool the world forever and that its tried and trite accusations of terrorism, while simultaneously being the principle perpetrator of it, have little import with the international community," said Qureshi in his message.
The PML-N also held rallies across Pakistan to express solidarity with Kashmiris.
In his message, Leader of the Opposition in the National Assembly Shehbaz Sharif said that the division of the Indian subcontinent will be complete only with the independence of Kashmir.
Addressing an event in Model Town, Shehbaz said: "If Pakistan is to help Kashmir in gaining independence, we need to fix our conduct.
"The whole country is united for Kashmir's independence but we will need to work hard. Imran Niazi has emptied the economy," he said.
Additionally, PPP Chairperson Bilawal Bhutto-Zardari said that there were no two views on the Kashmir issue in Pakistan. He added that the Kashmir issue should be solved on the basis of the local population's desires.
To express solidarity with Kashmiris on Black Day, various programmes were planned across Pakistan, Radio Pakistan reported, adding that Pakistani missions abroad were instructed to organise events with the Pakistani diaspora, local parliamentarians, think-tanks and others in order to highlight the significance of the day.
In Azad Jammu and Kashmir (AJK), the Kashmir Liberation Cell, Hurriyet and religious organisations organised rallies, demonstrations and protests. AJK Prime Minister Raja Farooq Haider presided over the main event in Muzaffarabad, where a rally was also taken out.
The Punjab government marked Black Day in collaboration with the federal government. Chairing a meeting of Kashmir Committee Punjab, law minister and committee chairman Basharat Raja said the longest and worst curfew in occupied Kashmir was extremely deplorable.
Additional reporting by Adnan Sheikh