The violent altercation took place on Saturday at about 10.27pm in Sea Front.
Witnesses reported seeing the victim being surrounded by a gang of a dozen youths before being assaulted near his home.
The 63-year-old was taken to Queen Alexandra Hospital with head and facial injures, police said, where he remains in a ‘stable condition’.
Police are investigating the attack. A referral has also been made to the Independent Office for Police Conduct (IOPC) in ‘relation to the circumstances surrounding the police response’, Hampshire Constabulary said.
A police spokeswoman added: ‘A 17-year-old boy from Hayling Island has been arrested on suspicion of section 18 grievous bodily harm. He has been released from police custody on conditional bail while our enquiries continue.
‘We are aware there may be some footage of the incident taken by witnesses. If you have any footage and haven’t spoken to officers already, please contact us as soon as possible. We would like to speak to anyone who witnessed the incident or anyone with any information.’
Locals living nearby to the attack said police were still in the area on Sunday afternoon.
Speaking of the incident, one 37-year-old mother who lives near the scene of the told The News: ‘I’m not fearful or scared of living here. This can happen anywhere really.
‘But I think the people that did this need to be punished. What happened was unacceptable.’
Those with information about the attack are urged to call 101 quoting 44220201782 or go online and submit information at hampshire.police.uk/tua/tell-us-about/cor/tell-us-about-existing-case-report/.