The former cricket hero shed a tear and smiled as he was officially handed the reins of power in a ceremony at the capital’s President House on Saturday.
The investiture marked only the second time in Pakistan’s 71 year history that there has been a peaceful democratic transition from one civilian government to another.
And it brought an end to decades of rotating leadership between the Pakistan Muslim League (Nawaz) and the Pakistan People’s Party, punctuated by military rule.
A tearful Mr Khan, dressed in a traditional black sherwani, promised to “bear true faith and allegiance”, and to “discharge my duties and perform my functions honestly, to the best of my ability... and always in the interest of the sovereignty, integrity, solidarity, wellbeing and prosperity of Pakistan”.
The 65-year-old – who became a national hero after captaining Pakistan to world cup victory in 1992 – had won a confidence vote in the National Assembly the previous day.
His taking up of office follows victory in the country’s July election in which his Pakistan Tehreek-e-Insaf party promised to end corruption and build an “Islamic welfare state”.
At Saturday’s ceremony,he was joined by members of that 1992 world cup winning team, including fast bowler Wasim Akram.
Another cricketer-turned-politician, India’s Navjot Singh Sidhu, was seated in the front row. In a sign that relations between the two countries may improve under Mr Khan, he was seen warmly embracing Pakistan’s army chief, General Qamar Javed Bajwa.
Mr Khan’s third wife Bushra Bibi, formerly known as Bushra Maneka, was also present, making her first public appearance since the couple married earlier this year. She was covered from head to toe in a white niqab.
His first wife, the London heiress Jemima Goldsmith – who he maintains a good relationship with – was not in attendance. Neither were the couple’s two sons. “The boys really wanted to be there but their father told them not to come,” Ms Goldsmith tweeted.
She has been one of her ex-husband’s biggest supporters, previously tweeting: “22 years later, after humiliations, hurdles and sacrifices, my sons’ father is Pakistan’s next PM. It’s an incredible lesson in tenacity, belief & refusal to accept defeat. The challenge now is to remember why he entered politics in the 1st place.”
After the swearing in ceremony, the new leader went to the prime minister’s house in the capital where he was given a guard of honour.
But the challenges now facing Mr Khan are myriad. No prime minister of Pakistan has ever completed a full five year term, and he will have to contend with the same issue as many of his predecessors: how to maintain a power balance in civil-military relations.
Dealing with militant extremism, water shortages, a rapidly growing population and a potential looming economic crisis are among the immediate issues awaiting Mr Khan.
There also remains strong opposition to his rule across the country. Many still claim his election victory was down to the military tilting the playing field in his favour with persistent accusations of vote rigging and intimidation – both of which the army and Mr Khan deny.
In a speech to parliament on Friday, he said: “I am here after 22 years of struggle. No dictator has taken care of me. I am standing here in this parliament on my own feet.”
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