Somerset's 168-run loss at Lancashire saw Surrey win the title with a round to spare and become champion for the 23rd time - 10 fewer than first-place Yorkshire in the all-time list.
Yorkshire was the last team to win the county championship three times in a row, from 1966-68.
Surrey, which plays its home games at The Oval in London, had already completed a win in the next-to-last round of matches by beating Durham by 10 wickets on Thursday.
Surrey's squad includes England test players Ollie Pope, Gus Atkinson, Jamie Smith and Dan Lawrence, as well as Kemar Roach of the West Indies.