The pair put on 198 for the first wicket as Tasmania reached 2-221 in pursuit of South Australia's 220 to ease to a bonus-point victory with 17.1 overs to spare in Brisbane.
Jewell punished the bowling from the outset and reached his century off just 71 balls, eventually finishing unbeaten on 126 in a 97-ball knock.
The 25-year-old left-hander crashed 20 boundaries and a six in a career-best score.
McDermott was similarly confident in scoring 71 before he was caught on the boundary off the bowling of Ben Manenti to end his 90-ball innings.
The match was effectively over as a contest by the time McDermott was dismissed with the openers scoring at a rollicking 6.6 an over.
Offspinner Manenti then picked up Tasmania skipper Jordan Silk for just seven as the former Tiger earned 2-44.
It was a very different experience at Allan Border Field for a South Australia side who picked up their own bonus-point win on Monday against Queensland.
Earlier, Tom Rogers starred with the ball as the Redbacks found batting a very different proposition.
The allrounder enjoyed significant movement both off the pitch and in the air to end with career-best figures of 5-32 from 10 challenging overs.
He knocked over Jake Weatherald and Redbacks' skipper Travis Head cheaply, as well as SA top-scorer Alex Carey.
Australia's Test wicketkeeper Carey looked confident in posting a half century only to fall for 59 from 45 deliveries.
Nathan McSweeney (29), Jake Lehmann (34) and Monday's player of the match Manenti (20) all made a contribution but the Redbacks' innings lasted just 44.1 overs.
Tasmania omitted former Test paceman Jackson Bird from the line-up head of a second game in Brisbane on Friday, this time against Queensland.
