[4][5][6] Saeed received his early education from Maulana Shabit, a local cleric in Orakzai Agency, before he moved south to Hangu District, Kohat Division, North-West Frontier Province (NWFP, now KPK) and attended Dar al-Uloom Islamia Hangu (Urdu: دار العلوم اسلامیه ہنگو) where one of his classmates, Maulana Shahidullah, remembered that Saeed had memorized the entire Quran in one year, was particularly peaceful, and would later marry his cousin, producing two sons and one daughter before taking another wife from North Waziristan Agency in the FATA (now a district in KPK).

[6][5] On 14 July 2012, as initial attempts by the United Nations to negotiate a ceasefire in the year-old Syrian civil war broke down and a full-fledged violent war began to emerge, Hafiz Saeed Khan agreed to rapidly assemble a group of 143 Afghan and Pakistani volunteer fighters for al-Qaeda (a TTP sponsor) to dispatch to Syria and join al-Qaeda's al-Nusra Front in the fight against Bashar al-Assad's brutal government.

Likely appreciative of the volunteer fighters supplied by groups in Afghanistan and Pakistan, the ISIS Military Commission in Syria offered ten TTP and Taliban volunteer group leaders from Saeed Khan's first dispatch $1 million to proselytize for the movement when they returned to Afghanistan and Pakistan with their jihadist combat experience, laying the groundwork for the later formation of ISIS–K.

[9][6][5] Having already pledged Bay'ah (allegiance) to the emir of the Islamic State of Iraq and Syria, Abu Bakr al-Baghdadi on 11 May 2013,[9] and now 42 years old, Saeed formally established Tehrik-e Khilafat Pakistan (Pashto: تحریک خلافت پاکستان, 'Caliphate Movement of Pakistan', TKP) under his leadership which would comprise nearly the entire Pakistani component of ISIS–K when TKP would merge with three Afghan groups in January 2015.

On 11 January 2015, Saeed and spokesman Shahidullah Shahid released a video message announcing the establishment of ISIS–K, an affiliate of the Islamic State in Khorasan Province.

According to the Department of the Treasury, "Khan, as leader of ISIL-K, plays a central role in expanding ISIL’s operations in the region, commanding militants and coordinating the delivery of supplies and munitions, the travel of associates, and other arrangements.

The Islamic State rejected the claim, but the strike did kill Shahidullah Shahid and Gul Zaman, according to senior ISIS–K leader Abdul Rahim Muslim Dost.

[13] On 12 August 2016, the United States announced that Hafiz Saeed Khan was killed on 26 July 2016 in a U.S. airstrike in Achin district of Afghanistan's Nangarhar Province.