Jones leaped 2.82m at the Vault Cardiff event held at the National Indoor Athletics Centre.
That was seven centimetres higher than he had leaped before.
Jones has just moved up to the under-15 age group, but his jump at the weekend puts him seventh in the early UK rankings and fourth in the English rankings.
Meanwhile, his City of Plymouth team-mate Poppy Tank enjoyed a good opening outing of 2018 in America.
Tank finished third in the mile race at the Bronco Invitational indoor event in Boise, Idaho.
Competing for the University of Utah, Tank clocked 5:01.26.
Closer to home, Tavistock Run Project’s Ben Neale won January’s 5kool Run on Saturday.
Neale clocked 16.11 minutes to win the Tavistock event by nearly a minute.
Second runner home was Royal Navy athlete Tom Bart, who finished in 17.06 minutes, with Plymouth Musketeers Alan Ryder third in 18.12.
First women home was Tavistock Run Project’s Rachel Malthouse, who clocked 19.45 minutes.
Tavistock Triathlon Club athletes Hannah Colston and Megan McCormick were second and third women home.
Full results of January’s 5kool Run can be found HERE.