Fraser-McGurk, 21, reached his half-century in 18 balls - the quickest by an Australian in one-day cricket.
He hammered six fours and 12 sixes en route to a maiden List A century.
Fraser-McGurk helped South Australia reach 172-0 in 11.4 overs at the Karen Rolton Oval in Adelaide before he fell to off-spinner Beau Webster having scored 125 runs from 38 deliveries, featuring 13 sixes and 10 fours.
List A cricket covers all white-ball one-day cricket which is longer than 20 overs per side (T20).
"I went out there with some good intent, had my plans and process, and seemed like everything went my way," said Fraser-McGurk, in what was his first century in professional cricket.
"I've made a few 30s playing in twos and stuff, felt like I've been hitting them reasonably well, but probably not that well so I definitely surprised myself."
Tasmania's total of 435-9 proved too much for South Australia to chase down, though, as they were bowled out for 398 with 20 balls remaining.
Tasmania captain Jordan Silk added: "It's probably an innings I'll never see maybe ever again. It was some of the cleanest ball-striking I've seen.
"Sometimes you've just got to tip your cap to players that can do that. While it was frustrating to watch, it was also amazing to watch."
