Finley Hassall saw a young boy drowning and encouraged him to swim on his back "like a starfish" to regain control of his breathing, helping him to stay calm until help arrived.
The 11-year-old, a pupil at Dingley Community Primary School in Dudley, had read the advice in a copy of the RNLI's Storm Force magazine.
Finley said: "I looked around and saw waves going over this boy’s head and he was splashing and struggling. He was clearly panicking.
"I’d read in my RNLI Storm Force magazine about how to float like a starfish so that’s what I asked him to do.
"I said I’d done this at my swimming lessons before and it will be fine if he could float on his back.
"He went onto his back and I was talking to him and trying to get him to take deep breaths to calm him down.
"An RNLI lifeguard soon arrived to check we were both okay and helped find the family of the boy before heading off to help two other people."
Guy Potter, the RNLI lifeguard who was on duty that day, has been reunited with Finley and presented him with a certificate to recognise his heroism.
In addition, Finley’s classmates were given a special safety presentation to ensure they have the same lifesaving knowledge should they be visiting the coast this summer.
Guy said: "Finley did a fantastic job. Being able to keep a clear and calm head in situations like this is really important.
"It was great to see his confidence grow as he put together what he’d learnt into a real-life scenario and really make a real difference."
The Royal National Lifeboat Institution (RNLI) and Her Majesty’s (HM) Coastguard are reminding families to take care when visiting the coast as new figures reveal that during the school summer holidays last year, 39 per cent of the 41 lives saved were children under 13.
As schools prepare to break RNLI beach lifeguards are expecting to be extremely busy again during the long summer break.
The RNLI and HM Coastguard are asking those visiting the coast to choose a lifeguarded beach and be aware of some basic advice to keep themselves and their families safe.
Last year RNLI lifeguards aided a total of 11,959 people during the school summer holidays last year.
Of those, children under the age of 13 were the most assisted age group with 4,968 aided and 16 lives saved.
Chris Cousens, from the RNLI Water Safety team, said: "With an estimated 35m people planning to visit the UK coast this summer, our lifeguards will be extremely busy during the school summer holidays with younger children, in particular, needing assistance more than any other age group.
"To stay safe, we’re reminding families to choose a lifeguarded beach where possible and swim between the red and yellow flags which is the safest area as it is constantly monitored by our highly-trained lifeguards.
"A simple skill we ask everyone of any age to remember is how to Float to live if they find themselves in difficulty in the water.
"Lean back like a starfish, using your arms and legs to stay afloat. This will allow you to control your breathing, then call for help or swim to safety. The technique has been proven to save lives."
Chris said: "The Float to Live technique is proven to save lives especially as we know that many people who find themselves in difficulty in the water never intended to enter the water in the first place."
Throughout the summer months, the children’s RNLI Seaside Safety advert will be broadcast on TV channels with the catchy song reminding those visiting the coast to float like a starfish if they find themselves in difficulty in the water.
The RNLI’s key water safety advice for all young people is:
Stop and think – Always swim in a safe place.
Stay together – Always swim with an adult, younger children should always be within arms reach.
Float – If you find yourself in trouble in the water, float on your back like a starfish.
Call 999 in an emergency and ask for the Coastguard.