Jarman eclipsed his England team-mate James Hall in a dramatic conclusion to the men's all-around gymnastics competition.
The 20-year-old rising star delivered a towering score of 15.3 on his favourite apparatus to seize the initiative before Hall, stricken by a foot injury, just failed to do enough to snatch the title on his concluding high bar routine.
Jarman finished with a score of 83.450, ahead of Hall's 82.9, with Marios Georgiou of Cyprus taking the bronze medal.
"I was quite nervous today," admitted Jarman. "I've done a European Championships before and I remember I struggled to keep everything together, but my team supported me and they really showed me I could do this.
"I normally do a different vault with a slightly lower start value but recently it's been a bit more inconsistent, so I decided to swap that up. The team final was the first time I had landed it in competition, but I really felt I could do it."
Jarman and Hall had teamed up to win the team final on Friday alongside Joe Fraser, who competed despite a fractured foot, and this time it was Hall who ended the session in pain after re-aggravating an ankle injury he had recently suffered in training.
Hall's evident discomfort might have made the difference as he hobbled off the stage after his parallel bars routine then stepped out his high bar landing, failing to attain a score in excess of 14.1 that would have elevated him into gold medal position.
Hall, also forced to settle for silver in 2018 behind the now-retired Nile Wilson, was typically magnanimous, insisting: "Jake did the hardest vault in the world today and he deserved it.
"It was immense out there. I've really got the crowd to thank for keeping me going. My coach said I could stop at any time but there was no way I could stop and I'm glad I didn't. I'm happy to take the silver in the circumstances."