| Official Name: | Blue Knob, Pennsylvania |
| Settlement Type: | Census-designated place |
| Pushpin Map: | Pennsylvania#USA |
| Pushpin Label: | Blue Knob |
| Pushpin Label Position: | top |
| Coordinates: | 40.3528°N -78.5533°W |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Pennsylvania |
| Subdivision Type2: | County |
| Subdivision Name2: | Blair |
| Subdivision Type3: | Township |
| Subdivision Name3: | Juniata |
| Area Footnotes: | [1] |
| Area Total Sq Mi: | 0.09 |
| Area Land Sq Mi: | 0.09 |
| Area Water Sq Mi: | 0.00 |
| Area Total Km2: | 0.23 |
| Area Land Km2: | 0.23 |
| Area Water Km2: | 0.00 |
| Unit Pref: | Imperial |
| Population Total: | 56 |
| Population As Of: | 2020 |
| Population Density Km2: | 238.80 |
| Population Density Sq Mi: | 615.38 |
| Timezone: | Eastern (EST) |
| Utc Offset: | -5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | -4 |
| Elevation Ft: | 2379 |
| Postal Code Type: | ZIP Codes |
| Postal Code: | 15946 (Portage) 16635 (Duncansville) |
| Area Codes: | 814/582 |
| Blank Name: | FIPS code |
| Blank Info: | 42-07272 |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2805467 |
Blue Knob is an unincorporated community and census-designated place (CDP) in Blair County, Pennsylvania, United States. It was first listed as a CDP prior to the 2020 census.
The CDP is in southwestern Blair County, at the southern end of Juniata Township. It stands atop the Allegheny Front at elevation, approximately southeast of the Eastern Continental Divide. Pennsylvania Route 164 passes through the community, leading east down the Front 7miles to East Freedom and west 8miles to Portage. Knob Road leads south from the CDP 5miles to Blue Knob State Park, atop Blue Knob, the second-highest peak in Pennsylvania.