Police said a 44-year-old man was arrested following the incident in St Helen’s Road at 4.10pm on Wednesday (August 25).
A police spokesman said a Fiat Panda was reported to have collided with the pedestrian, a 78-year-old local woman.
She was airlifted to the Royal Sussex County Hospital in Brighton with life-threatening injuries, police said.
A 44-year-old man from Hastings was arrested on suspicion of causing serious injury by dangerous driving and has been released under investigation, police added.
Witnesses or anyone with CCTV or dashcam footage of the incident is asked to email: [email protected] quoting Operation Extase.