| Honorific-Prefix: | Honourable |
| J. I. Gnanamuttu | |
| Honorific-Suffix: | MSC |
| Office1: | Member of the State Council of Ceylon |
| Constituency1: | Mannar-Mullaitivu |
| Term Start1: | 1943 |
| Term End1: | 1944 |
| Predecessor1: | R. Sri Pathmanathan |
| Successor1: | J. Tyagaraja |
| Blank1: | Ethnicity |
| Data1: | Ceylon Tamil |
Joseph Isaac Gnanamuttu (died 19 January 1944) was a Ceylon Tamil politician and member of the State Council of Ceylon.
Gnanamuttu contested the 1943 State Council by-election as a candidate in Mannar-Mullaitivu and was elected to the State Council of Ceylon.[1] [2] He died on 19 January 1944.[1]