Starting at 87th floor of the Shard, just below the top of the 1,016ft structure, the Queen's second son took 30 minutes to make his way down to floor 20 – and said he would never do it again.
By the time he'd finished his descent, the war veteran, who served as a pilot in the Falklands, had raised £290,000 for the Outward Bound Trust and the Royal Marines Charitable Trust Fund.
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Donors included his daugher Princess Eugenie, who gave £500, saying: "Well done papa! I'm so proud of you".
Meanwhile, his friend Kazakhstani socialite Goga Ashkenazi promised £5000 for the fund, which will go towards outdoor activities for children in inner cities.
Although he must feel it was worth it, the Prince admitted it had been tough.
He said: "I'm not even going to say that was a piece of cake or not. I will never do it again. I have to say, the most difficult bit was walking up the stairs."
And what did his mother think of the daredevil stunt?
"When I spoke to her she was interested in why we were doing it and when I spoke to her about all the safety and the activities that were going on around it, about the teamwork... she understood what all the risks were and, like the incredible monarch she is, she was entirely happy.
"But this is not about me, this is about young people, this is about young people's future, this is about changing people's lives and giving them the opportunity."
Others that abseiled included Ffion Hague, the wife of Foreign Secretary William Hague, and leading businessmen and women.
She said said the abseil was "scary, exhilarating and truly terrifying".
"I am very glad it is over and I wouldn't necessarily want to do it again but, my goodness, I am glad I have done it," she added.