Open Settings → Personal Hotspot and enable Allow Others to Join when your carrier and plan support it.
Step by Step
- Confirm cellular data is working.
- Open Settings.
- Select Personal Hotspot, or Cellular → Personal Hotspot on some versions.
- Turn on Allow Others to Join.
- Note the Wi-Fi password.
- Connect the other device to the iPhone's hotspot.
If That Doesn't Work
- Availability and data limits depend on the cellular plan.
- Hotspot use can consume battery and cellular data quickly.