Renshaw hit 106 from 75 balls for the hosts in Darwin on Sunday as Australia A lost 8-65 to be all out for 243 in reply to the visitors' 7-294.
The Queenslander's century included nine boundaries and two sixes, coming after he also hit 80 in an emphatic win over Sri Lanka A on Friday.
Renshaw drove powerfully against the spinners, hitting Dushan Hemantha inside-out over cover for a six and plundering several boundaries through the region.
He brought up his century off 70 balls when he worked Mohamed Shiraz to the the fine-leg boundary, before holing out in the deep off Hematha shortly after.
After initially being considered one of the country's most conservative batters, Renshaw has risen to power in the white-ball game in recent years.
South Australia's Liam Scott also contributed, making 53 before the Australia A tail fell apart and medium-pacer Pramod Madushan finished with 4-37.
Earlier, Australia A's bowlers struggled to make inroads with Jack Nisbett finishing with 2-58 from his 10 overs and Sam Elliott 2-30 off three overs..
Renshaw's spinners also came in handy as he took 1-31 from eight overs.
Sri Lanka's innings was built around Nuwanidu Fernando's stylish 82 from 90 balls, laced with two sixes and five fours.
And opener Lasith Croospulle also struck a half-century, hitting two sixes in his 63 from 70 deliveries.
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