The teenager, who cannot be named for legal reasons, appeared at Worthing Youth Court on Thursday (23 January) charged with two counts of causing actual bodily harm, police said.
Police were alerted by a member of the public to an assault involving a father and son in Durrington on 13 May.
Officers were able to identify the teenager involved in the assault and he was arrested and charged, police confirmed.
He was given a four month referral order to the youth offending services, a £20 victim surcharge and £40 court costs, police said.
Chief Inspector Sarah Leadbeatter District Commander for Adur and Worthing said: “This was a targeted assault on a particular child and when his father stepped in, he too was injured.
“This teenager used fear, intimidation and violence towards his victims and showed little regard to the distress he was causing.
“I would like to personally thank the victims in this case who have shown incredible strength and courage to come forward and report this incident to us.
“Their support with the investigation has been invaluable and allowed us to bring the offender to justice.
“Although the victims in this case have physically recovered from their injuries, the psychological injuries may still remain, but I hope the conclusion of this criminal investigation goes some way to starting that healing process.
“Tackling serious youth related violence across our district continues to remain my priority and we remain engaged with our communities in order to address local concerns and build on community intelligence.
“This is the first wave of court cases for a group of youths involved in violence and I would like to praise our partners for the multi-agency working we have all been undertaking and this work will continue to address this issue.
“We continue to need the support of our local community and there are many ways you can report matters of concern through contacting us either online or by calling 101, the independent charity Crimestoppers or Fearless.
“If you or you see someone in danger please dial 999.”