Andrzej Sapkowski appears to have spent about two years writing the latest Witcher book, based on his own comment that it “took me two years, something like this.”

Context

That figure refers to the newer standalone Witcher novel , not the entire Witcher series, which began with his first short story in 1986 and grew over many years.

Quick answer

  • Latest book: about 2 years.
  • Whole Witcher universe: built over decades, starting in 1986.

Note

If you meant the original Witcher stories and novels as a whole, there isn’t one single writing time, because Sapkowski published them across many years rather than writing the entire series in one stretch.