Can You Play PSP UMDs in a GameCube? No.

Absolutely not.

• PSP: UMD (Universal Media Disc) – 60mm, 1.8GB, cartridge-like casing.
• GameCube: GameCube Game Disc (MiniDVD) – 80mm, 1.5GB, standard DVD structure.

Different physical size, laser wavelength, tracking, file system, encryption, and drive mechanics. The GameCube drive cannot physically accept a UMD; the PSP drive cannot read a MiniDVD.

To play PSP games on TV: Use PSP 2000/3000/Go with Component/Composite AV cable (or HDMI mod), or PPSSPP emulator on PC/Phone/Deck connected to TV.