There are four Simple Keys in Hollow Knight: Silksong.

Quick Scoop

  • Silksong has a total of four Simple Keys that you can find in a single playthrough.
  • These four keys are used to open four specific Simple Key locks/doors around Pharloom, each leading to shortcuts or reward areas.
  • Guides and wikis agree on this fixed count, so you do not need to worry about missable extra Simple Keys beyond those four.

In short: if you have four Simple Keys, you’ve hit the cap for how many Simple Keys are in Silksong.

Information gathered from public forums or data available on the internet and portrayed here.