In 1999, Grayken became an Irish citizen, "for tax purposes", renouncing his American citizenship.
As of 2015, they owned Pyrford Court, Surrey, which features prominently in the 1976 movie, The Omen. Pyrford Court is a Grade II listed 15-bedroom house, built in 1910 for Rupert Guinness, 2nd Earl of Iveagh. As of 2017, they live in a $70 million home in Chelsea, London, purchased through a company in Bermuda.
In April 2017, John P. Grayken gave a leadership gift to the Wharton School of the University of Pennsylvania to fund the Grayken Program in International Real Estate at the Wharton School.