The animal was discovered washed up on the beach near Hove Lawns on Sunday morning.
Shoreham Coastguard responded to the discovery and shared a photograph of the dolphin alongside a warning.
The dolphin’s body is still on the beach.
The area was cordoned off and people have been advised to keep their distance, especially if they have dogs.
(Image: HM Coastguard Shoreham)
A spokesman from Brighton and Hove City Council said: “Seafront officers discovered a dead dolphin on the beach during their morning patrol.
“The area was made safe and cordoned off with hazard tape while officers contacted the specialist contractor responsible for removing deceased animals from our beaches.
“For the safety of both the public and pets, we kindly ask that dogs are kept well away from the dolphin and that the animal is not approached or touched.
“At this stage, the cause of death is unknown. While unfortunate, it is not uncommon for deceased marine animals to wash ashore from time to time.
“Thank you for your cooperation.”
HM Coastguard Shoreham said: “On Sunday, August 30, our team was paged to a washed up dolphin at Hove Lawns.
“Coastguard are aware, and we have notified the local council to arrange collection and disposal.”
Animals found around the UK coastline can be reported to the UK Cetacean Strandings Investigation Programme, which records strandings and may examine some animals to help determine how they died.
Members of the public and their pets are advised not to touch or approach a stranded animal due to risk of injury or disease.