Berry is just 13, but was chosen to represent England Under-16s in an event involving top juniors from around the world.
Despite conceding a three-year age gap to many of his competitors over the Eden course the French Under-14 champion was third overnight.
He began at the 10th and parred every hole up to and including the 18th, missing a few good chances to make birdie on his 'outward' nine.
He made it 14 pars in a row with regulation scores at holes one to five before dropping a shot at the sixth.
Berry hit back in superb style with gains at holes seven, eight and nine.
He was 'out' in level-par 35 and 'home' in two-under 33.
Past winners of the biennial R&A’s Junior British Open include current Masters champion Patrick Reed, who triumphed at Heswall in 2006.
Six years after its creation in 1994 the Junior Open Championship came under the R&A’s administrative umbrella.
All golfing nations affiliated to the R&A are invited to enter their best Under-16 boy and girl golfers.
The event is closely linked to the Open which starts at Carnoustie on Thursday - and is always played on a nearby course.
Berry’s multiple successes include him becoming French Under-14 champion earlier this year, the first English player to win the Chantilly International Trophy in its 45-year history.
He followed that by making his debut for England Under-16s against the North West at Alwoodley, for the Sheffield Union scratch team, and for Yorkshire Under-18s.
It is only three years since he began playing golf and he made his mark immediately when, aged 10, he overhauled an eight-shot first-round deficit to win the 36-hole adidas British Wee Wonders championship on the Strathtyrum course, St Andrews.
Last year he won the title for an unprecedented second time, his 65 setting a course record that surpassed the previous efforts of Ryder Cup player Matt Fitzpatrick and the Sheffielder’s fellow European Tour winners Tyrrell Hatton and Tommy Fleetwood.