There is no official version of Resident Evil 4 for the PlayStation Portable (PSP). While Capcom has ported the game to nearly every other platform—including GameCube, PS2, PC, Wii, Android, and even the obscure Zeebo—the PSP was never officially supported. Why You Can't Find an Official ISO/CSO
If you find a legitimate fan-made ISO/CSO, your PSP must meet these requirements: Custom Firmware (CFW): Download Resident Evil 4 Psp Iso Cso
However, the keyword "Download Resident Evil 4 PSP ISO CSO" persists because of the sheer novelty. Holding the entire village, castle, and island in your pocket on a 20-year-old Sony handheld remains a technical marvel of the homebrew community. There is no official version of Resident Evil
Despite being ported to almost every other platform—including the GameCube, PS2, Wii, mobile phones, and even the obscure Zeebo console—the PSP was skipped, likely due to hardware limitations at the time. Holding the entire village, castle, and island in
Alternatively, you can convert the game from a UMD (Universal Media Disc) or obtain it from a digital store, then convert it to a CSO/ISO file.
Since there is no official ISO, many sites claiming to offer a "High Compressed Resident Evil 4 PSP ISO" may actually be providing: Malware or Adware: Files bundled with harmful software.