Purvis had to be content with silver for the second successive year as he lost out to England's Max Whitlock. Fellow Scot Daniel Keatings took bronze.
Purvis, who won the title from 2010-12, suffered an agonising fall on his final tumble in the floor routine, his penultimate piece, and it kept his mark down to 13.750 points.
Keatings was just 0.2 points behind Whitlock going into the final rotation but a fall on the high bar left him unable to overhaul the Englishman. He scored 13.150 points, to finish with an all-around total of 87.050 points.
Whitlock finished on 89.000 points to retain his title.
Purvis, who won gold on rings, and bronze on high bar, was disappointed at missing out on the top title.
"It was a mixed competition from my point of view," he said. "I struggled on vault but managed to land it safely, which is fine.
"Everything else was fine but I don't know what happened on the floor. However, I finished strongly on pommels so I'm happy with that.
"I am happy finishing in the top two after the floor and I would have been quite disappointed not to finish in the top three. It was great I still managed to pull it back."
Keatings, who also won bronze on floor, silver on pommel, and gold on parallel bars, was delighted with his progress on his return to competing on all six pieces of apparatus.
"It was really good. It is the first time I have done the all-around in a British Championships since 2012. I have only been training for this for the past six months, so I wasn't really expecting that.
"I was hoping to just come and put in a performance but coming away with a bronze, I am really happy."
Teenager Rebecca Tunney, the youngest member of Team GB at London 2012, won the women's competition with a score of 56.750 ahead of Beckie Downie (56.350) and first-year senior Claudia Fragapane (55.700).
The event is the last trial for Commonwealth Games selection for English gymnasts and Whitlock impressed, topping the standings in the floor and pommel horse.