Leo, from South Wales, was visiting Sully beach near the Captain’s Wife pub with his dad Ash when he noticed two boys in trouble near Sully Island.
Despite his autism and global development delay, which make communication difficult, he told his dad that he thought the boys needed help.
Ash said: “I’m so unbelievably proud of Leo and what he did that day.
“Because of his significant challenges, I was surprised and so impressed that he was able to show the level of awareness and do the right thing by telling me that he thought two boys were in trouble.
“When I looked towards the island and realised what was happening, I knew we needed to get help straight away.”
Ash immediately called HM Coastguard and stayed on the phone while the rescue began.
Barry Dock RNLI launched their D-class inshore lifeboat to reach the boys, who were caught by the fast-rising tide and strong currents.
Both boys were brought safely ashore.
Ash said: “I’m so pleased that Leo spotted them and spoke up.
“It could have been a very different story if he hadn’t raised the alarm.
“Seeing him recognised by the RNLI has been wonderful.
“He absolutely deserves it, and I couldn’t be prouder of him.”
The crew at Barry Dock RNLI were so impressed by Leo’s actions that they invited him and his dad to visit the lifeboat station to thank him personally.
During the visit, Leo was given a tour of the all-weather lifeboat and the inshore lifeboat, and met members of the crew.
Coxswain Andy Gavan said: “Leo is an absolutely brilliant young man, and it was a real pleasure to welcome him and his dad to the station.
“What makes this story so special is that Leo spotted something was wrong and made sure his dad knew about it.
“He recognised that those boys needed help, and he spoke up.
“His actions meant that his dad was able to raise the alarm and get help on its way and we wanted him to know just how much we appreciated what he did.
“It was lovely to show him around the station, introduce him to some of the crew and present him with his certificate.
“He’s a real star.”
The rescue also highlights the danger of rapidly changing tides around Sully Island, where people are often caught out by incoming water and strong currents.
The RNLI is reminding the public to check tide times, allow plenty of time to return safely, and to never attempt a rescue themselves.
