OPB may refer to:

• Obscene Publications Branch, a former unit of the Metropolitan Police in London, England
• Oregon Public Broadcasting, a radio and television network based in the U.S. state of Oregon
• Oregon Progress Board, a commission of the Oregon state government
• Xilinx On-chip Peripheral Bus, a low-speed bus for connecting peripherals within a Xilinx system on a chip
• In music, sometimes used as an abbreviation for "originally performed by"
• Oakridge Project Bloods, a Bloods gang in Oak Ridge, Tennessee.