A statement said that the "royal couple want to meet as many Pakistanis as possible during their visit".
It is not clear if the Duke and Duchess will see Khan again after Tuesday.
Kate arrived at the college dressed in a royal blue classic kurta with pants and dupatta by Pakistani designer Maheen Khan.
They will be taking part in a five-day tour of the country. William's mother Princess Diana, a hugely popular figure in Pakistan, visited Pakistan several times in the 1990s and helped Khan raise money for a cancer hospital.
The traditional Pakistani salwar kameez, paired with a dupatta, bore a striking resemblance to Princess Diana's dark blue suit that she wore during her Pakistan visit.
British High Commissioner in Pakistan Thomas Drew and senior Pakistani officials were also at a military airbase to receive the couple.
The Duke and Duchess of Cambridge arrive for their visit to Pakistan.
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For security reasons, authorities shared limited details about William and Kate's itinerary, which is expected to include a visit to the country's scenic northern provinces and the historic eastern city of Lahore.
Their five-day-tour will "largely focus on showcasing Pakistan as it is today - a dynamic, aspirational and forward-looking nation". They will also visit programmes aiming to empower people and learn how communities are adapting to climate change. The Prime Minister apprised the royal couple of domestic priorities and Pakistan's perspective on external environment, including relations with India following the abrogation of the special status of Jammu and Kashmir under Article 370 in August and reconciliation in Afghanistan.
They then visited the Margallah Hills National Park on the edge of Islamabad, which is under threat from poaching, wildfires, invasive species and littering. Security arrangements for their arrival are already in place.
It has been billed as their "most complex" tour to date by the palace due to the complex security picture in the region.
It said Khan "recalled the love and affection among the people of Pakistan for Princess Diana, because of her compassion as well as commitment to support charitable causes".
In his address, William is expected to say that the United Kingdom will continue to support the Commonwealth country as a "key partner and friend" during a visit which hopes to strengthen ties between the two nations.