Isserlis was born in London into a musical Jewish family on 19 December 1958. His grandfather, was one of 12 musicians allowed to leave Russia in the 1920s to promote Russian culture, but he never returned. His sister Annette Isserlis is a violist and his other sister Rachel Isserlis is a violinist. He went to the City of London School. He left school at the age of 14 years and then moved to Scotland to be a student of Jane Cowan. He is a Beatles fan and his long hairstyle is inspired by the Beatles. His family were supportive of his music career when he was not earning much money.
He is married to Pauline, a former flute player, and they have a son, Gabriel.
He was awarded a CBE in 1998, and collected his award with his father, as his mother died earlier that week. He was awarded the Schumann Prize 2000 by the city of Zwickau. He plays the Feuermann Stradivarius, on loan from The Nippon Music Foundation. He also part-owns a Montagnana cello from 1740 and a Guadagnini cello of 1745, which he played exclusively from 1979 to 1998 and part-owns with David Waterman, cellist of the Endellion Quartet.
He is also the author of two books for children on the lives of famous composers: the first is Why Beethoven Threw the Stew (Faber & Faber, 2001), and the second Why Handel Waggled His Wig (Faber & Faber, 2006).
Isserlis is Artistic Director of the International Musicians Seminar, Prussia Cove in West Cornwall, where he both performs and teaches.