| Named By: | L. S. Russel in 1968 |
| Time Period: | Oligocene |
| Location: | Canada, British Columbia - Sooke Formation, and the USA, Washington - Pysht Formation |
| Size: | Skull about 40 centimetres long |
| Diet: | Uncertain |
| Fossil(s): | Almost complete skulls and partial post cranial remains |
| Classification: | | Chordata | Mammalia | Cetacea | Aetiocetidae | |
Chonecetus is an extinct genus of primitive baleen whale of the family Aetiocetidae that lived in the Oligocene period. Its fossils have been found in Canada, in the northeast Pacific. It was first named by L.S. Russell in 1968, and contains one species, C. sookensis.
Like Aetiocetus, Chonecetus possessed both multicusped teeth and the nutrient foramina required for baleen. Chonecetus closely resembled a modern Mysticeti, with an elongate, streamlined body supporting a pair of paddle-shaped forelimbs, and a horizontal tail fluke strengthened by fibrous cartilage.