Labuschagne cracked 105 off 91 balls to lead Queensland to 311 of 45.3 overs at Allan Border Field on Thursday.
In reply, Tasmania reached the victory target with 10 balls to spare courtesy of big knocks from Tim Ward (105 off 96 balls), Jordan Silk (85no off 61) and Caleb Jewell (79 off 76).
Tasmania (3-0) remain unbeaten on top of the table, while Queensland slipped to a 2-1 record.
Labuschagne's big knock came just days after he scored 160 off 206 balls in Queensland's Sheffield Shield draw with Tasmania, following on from his 130 off 118 balls in the Bulls' One-Day Cup opener against Victoria last month.
The hot run of form comes at the perfect time for Labuschagne, who is in the midst of a huge bat-off for an Ashes spot at the top of the order.
Labuschagne is competing with the likes of Sam Konstas, Cameron Bancroft, Marcus Harris, Nathan McSweeney, Jake Weatherald and Matt Renshaw to partner Usman Khawaja as opener for the five-Test series against England.
There is also the option of Labuschagne returning to his preferred No.3 position if selectors opt not to pick allrounder Beau Webster, who is battling an ankle injury.
Labuschagne cracked eight fours and two sixes in his sparkling knock on Thursday.
The 31-year-old was dropped on 91 when spinner Nikhil Chaudhary (3-66) couldn't hold on to a sizzling return chance.
Labuschagne punched Chaudhary for four behind point to bring up his ton off 89 balls, but he was out a short time later when he edged the Indian-born spinner behind.Â
The exit of Labuschagne sparked a collapse of 7-70 as Queensland failed to capitalise on a strong start.
Matt Renshaw, who was called up ahead of Labuschagne for the upcoming ODI series against India, scored 38 off 35 balls.
Labuschagne's most recent Test century came against England in 2023, with his lean run of form since then resulting in his axing for the 3-0 series win over the West Indies.
His ODI snub this week added further salt to the wound, but Labuschagne replied in perfect style with his ton on Thursday.
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